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Male sex steroids are responsible for depressing
macrophage immune function after trauma-hemorrhage
MATTHIAS W. WICHMANN, ALFRED AYALA, AND IRSHAD H. CHAUDRY
Center for Surgical Research and Department of Surgery, Brown University School
of Medicine and Rhode Island Hospital, Providence, Rhode Island 02903
immunity; interleukins; testosterone
carried out in recent
years to investigate the effects of hemorrhagic shock,
alone or in conjunction with soft tissue trauma, on
cell-mediated and humoral immunity (2, 7, 19–21, 28).
Such studies have clearly indicated a marked depression of host immune functions following hemorrhagic
shock, which were detectable immediately after the
hypotensive period and persisted for a prolonged period
of time (2, 19, 20). Soft tissue trauma per se is also
known to cause a severe depression of cell-mediated
and humoral immune function (1, 21). In view of the
above, it is not surprising that the combination of soft
tissue trauma and hemorrhagic shock produces a more
sustained depression of immune functions (7, 21, 28).
Significant endocrine alterations have been reported
following major blood loss, including increased release
of adrenocorticotropic hormone, corticosterone, and bendorphin (15). Despite the fact that gender differences
in the susceptibility to and morbidity from sepsis have
been observed in several clinical and epidemiological
studies (5, 6, 14), the alterations in endocrine and
NUMEROUS STUDIES HAVE BEEN
immune functions have been investigated primarily
using male laboratory animals. Immune function in
normal males and females has been reported to be
influenced by sex steroids (10). In this regard, it
appears that better-maintained immune functions in
females are due not only to physiological levels of
female sex steroids typically present but also at least in
part due to the absence of immunosuppressive male
androgenic hormones (13). A number of clinical and
experimental studies have shown the suppressive effects of androgens on immunity (13, 17, 22, 24). For
instance, it has been reported that not only the peripheral B cell fraction is enlarged in androgen-deficient
mice but that the production of interleukin-2 (IL-2) and
interferon-g is increased in peripheral T cells (22).
Moreover, in a murine model of lupus erythematosus,
survival was prolonged by androgen therapy (17). On
the other hand, accelerated death from lupus was
observed when the androgen receptor blocker flutamide
was administered (24). Furthermore, recent immunological studies suggest beneficial effects of castration on
splenocyte immune function after soft tissue trauma
and hemorrhagic shock (26).
Nonetheless, it remains unknown whether androgens are also involved in depressing macrophagedependent immune function following trauma-hemorrhage. It also remains unknown whether castration
(i.e., testosterone depletion) before trauma-hemorrhage has any salutary effects on macrophage immune
function following soft tissue trauma and hemorrhagic
shock. This appears to be of importance, since antiandrogen therapy could have beneficial effects on immune functions following soft tissue trauma and/or
hemorrhagic shock in the clinical situation. The aim of
the present study, therefore, was to determine the
effects of castration on splenic and peritoneal macrophage function following soft tissue trauma and hemorrhagic shock as indicated by IL-1 and IL-6 release.
Furthermore, the release of IL-6 by Kupffer cells was
measured. These cells are believed to contribute to the
systemic inflammatory response following traumahemorrhage through the increased release of IL-6
under those conditions (3, 16).
MATERIALS AND METHODS
Animals
Inbred male C3H/HeN mice (9–11 wk old, 24–26 g body wt;
Charles River Laboratories, Portage, MI) were used in this
study. All procedures were carried out in accordance with the
guidelines set forth in the Animal Welfare Act and the Guide
for the Care and Use of Laboratory Animals by the National
Institutes of Health. This project was approved by the
0363-6143/97 $5.00 Copyright r 1997 the American Physiological Society
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Wichmann, Matthias W., Alfred Ayala, and Irshad H.
Chaudry. Male sex steroids are responsible for depressing
macrophage immune function after trauma-hemorrhage. Am.
J. Physiol. 273 (Cell Physiol. 42): C1335–C1340, 1997.—
Recent studies suggest beneficial effects of castration before
soft tissue trauma and hemorrhagic shock on splenocyte
immune functions. Nonetheless, it remains unknown whether
this effect of testosterone depletion is limited to splenocytes or
is a generalized effect on immune function. The present study
was therefore carried out to determine whether androgen
depletion before trauma-hemorrhage also has salutary effects
on splenic and peritoneal macrophage as well as on Kupffer
cell function, as indicated by interleukin (IL)-1 and IL-6
release. Male C3H/HeN mice were castrated or shamcastrated 2 wk before the experiment and were killed at 24 h
after trauma-hemorrhage and resuscitation. Significant depression of macrophage IL-1 and IL-6 release was only
observed in sham-castrated mice, as opposed to normal levels
of cytokine release from castrated animals after traumahemorrhage. In addition, only sham-castrated animals showed
significantly increased levels of IL-6 release from Kupffer
cells, which is believed to contribute to the systemic inflammatory response to trauma-hemorrhage. These observations
suggest that the beneficial effects of androgen depletion
before trauma-hemorrhage are not limited to splenocyte
immune functions but are more global in nature. These
results in surgically castrated animals suggest that androgenblocking agents should be studied for their potential to
reverse the immunodepression associated with traumahemorrhage.
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MALE SEX STEROIDS AND MACROPHAGE FUNCTION
Institutional Animal Care and Use Committee of Brown
University and Rhode Island Hospital.
Experimental Groups and Procedures
Plasma Collection and Storage
Whole blood was obtained by cardiac puncture and was
placed in prechilled EDTA-containing microcentrifuge tubes
(Microtainer; Becton Dickinson, Rutherford, NJ), which were
kept on crushed ice. The tubes were then centrifuged at
16,000 g for 15 min in a refrigerated (4°C) room. Plasma was
separated, placed in pyrogen-free microcentrifuge tubes, immediately frozen, and stored (280°C) until the time of assay.
Preparation of Kupffer Cell Culture
After sterile collection of peritoneal macrophages, the
peritoneal cavity was packed with sterile gauze. The liver was
then blanched to remove cellular blood components by a
retrograde perfusion with 30–40 ml of ice-cold Hanks’ balanced salt solution (HBSS) through the portal vein. This was
immediately followed by perfusion with 10 ml of 0.05%
collagenase class IV (Worthington Biochemical, Freehold,
NJ) in HBSS at 37°C. The liver was removed en bloc and
transferred to a petri dish containing warm enzyme-HBSS.
The tissue was then minced finely, incubated at 37°C for 15
min, and passed through a sterile 150-mesh stainless steel
screen into a beaker containing 10 ml of cold HBSS and 10%
FBS (Biologos, Naperville, IL). The cell suspension was
centrifuged at 1,200 g for 15 min at 4°C, the supernatant was
removed, and the cell pellet was resuspended in HBSS and
washed by centrifugation. The cell suspension was then
layered over a 16% Metrizamide (Accurate Chemical, Westbury, NY) in HBSS and centrifuged at 3,000 g, 4°C, for 45 min
in a preparative ultracentrifuge. This process separates the
Kupffer cells (which form a band at the Metrizamide cushion
interface) from the remaining parenchymal cells in the pellet.
After removal of the nonparenchymal cells from the interface
with a Pasteur pipette, the cells were washed twice by
centrifugation (800 g, 10 min, 4°C) with HBSS. The pellet was
then dispersed and resuspended in Click’s medium containing 10% FBS. The cells were transferred to a petri dish and
incubated for 4 h at 37°C (5% CO2 ). Nonadherent and
nonviable cells were then removed by three repeated washings of the dish. This protocol provides adherent cells that are
.96% positive by nonspecific esterase staining and that
exhibit typical macrophage morphology (3). The capacity of
mouse Kupffer cells to produce IL-6 was determined by
assaying the supernatants taken from these cells (3 3 106
Kupffer cells · ml21 · well21 ) following a 24-h incubation (37°C,
5% CO2 ) with or without 10 µg LPS/ml Click’s medium with
10% FBS.
Preparation of Splenic Macrophage Culture
The spleens were removed aseptically and placed in separate petri dishes containing cold (4°C) phosphate-buffered
saline (PBS) solution. The splenocyte suspension was used to
establish a macrophage culture as previously described (18).
The splenic macrophage monolayer was stimulated to produce cytokines by incubation with 10 µg LPS (from Escherichia coli 055:B5; Difco Labs, Detroit, MI) per milliliter in
Click’s medium with 10% FBS for 48 h at 37°C, 5% CO2, and
90% humidity. At the end of the incubation period, the culture
supernatants were removed, divided into aliquots, and stored
at 280°C until assayed for IL-1 and IL-6.
Preparation of Peritoneal Macrophage Culture
Resident peritoneal macrophages were obtained from mice,
as previously described (4), and a monolayer was established
as previously described (18). The macrophage monolayers
were stimulated in vitro with 10 µg lipopolysaccharide W
(LPS)/ml Click’s medium containing 10% fetal bovine serum
(FBS) for 48 h at 37°C, 5% CO2, and 90% humidity, to assess
Cell Line Maintenance
The IL-1-dependent D10.G4.1 cells (a gift from Dr. Charles
Janeway) were maintained as described by Ihle et al. (12).
The IL-6-sensitive murine B cell hybridoma (7TD1; a gift
from Dr. Jacques Van Snick) was maintained as previously
described (12).
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Mice were subjected to sham-castration or castration at the
age of 7 wk, i.e., 2 wk before the initiation of the experiment.
The castration procedure was performed as previously described by Waynforth (24). All mice were then randomized
into one of four groups. Groups 1 and 2 consisted of castrated
animals. Animals in group 1 were sham-operated controls for
the trauma-hemorrhage procedure, and the animals in group
2 underwent a combined model of soft tissue trauma and
hemorrhagic shock. The animals in groups 3 and 4 were
sham-castrated, with the animals in group 3 serving as
sham-operated controls and the animals in group 4 undergoing the combined trauma-hemorrhage model. Mice in the
trauma-hemorrhage groups were lightly anesthetized with
methoxyflurane (Metofane; Pitman-Moore, Mundelein, IL)
and restrained in a supine position, and a 2.5-cm midline
laparotomy (e.g., trauma-induced) was performed. The abdominal incision was then closed aseptically in two layers
using 6–0 Ethilon sutures (Ethicon, Somerville, NJ). After
this, both femoral arteries were aseptically cannulated with
polyethylene 10 tubing (Clay-Adams, Parsippany, NJ) using a
minimal dissection technique. The animals were then heparinized (2 units beef of lung heparin/25 g body wt; Upjohn Labs,
Kalamazoo, MI) and allowed to awaken. Blood pressure was
constantly monitored by attaching one of the catheters to a
blood pressure analyzer (Digi-Med, Louisville, KY). The areas
of incision were then bathed with 1% lidocaine, and the
animals were allowed to awaken. When they awakened, the
animals were bled through the other catheter to a mean blood
pressure of 35 6 5 mmHg (blood pressure prehemorrhage was
,95 6 5 mmHg), which was maintained for 90 min.
At the end of the hypotensive period, the shed blood was
returned to the hemorrhaged animals, and lactated Ringer
solution (23 the shed blood volume) was infused to provide
adequate fluid resuscitation. The catheters were then removed, the vessels were ligated, and the groin incisions were
closed. Sham-operated animals in groups 1 and 2 underwent
the same surgical procedure, which included heparinization
and ligation of both femoral arteries, but soft tissue traumahemorrhage and fluid resuscitation were not carried out. All
animals were killed by methoxyflurane overdose at 24 h after
initiation of the experiment, to obtain whole blood from the
heart and macrophages from the peritoneal cavity, the spleen,
and the liver. All mice were killed at the same time point to
avoid artifacts due to marked circadian fluctuations of plasma
hormone levels.
the cells’ ability to release IL-1 and IL-6. At the end of the
incubation period, the culture supernatants were removed,
divided into aliquots, and stored at 280°C until assayed for
IL-1 and IL-6. This protocol provided adherent cells that were
.99% positive by nonspecific esterase staining and that
exhibited typical macrophage morphology.
MALE SEX STEROIDS AND MACROPHAGE FUNCTION
C1337
Assessment of Cytokine Release
Radioimmunoassay
Plasma testosterone concentration was determined using a
commercially available radioimmunoassay (RIA) kit (ICN
Biomedicals, Costa Mesa, CA). In this Immuchem doubleantibody RIA kit, 50-µl plasma samples were assayed in
duplicate. The cross-reactivity of the RIA for testosterone was
found to be 100%. For other steroids, the cross-reactivity was
as follows: 3.40% for 5a-dihydrotestosterone, 2.20% for 5aandrostane-3b,17b-diol, 2.00% for 11-oxotestosterone, 0.95%
for 6b-hydroxytestosterone, 0.71% for 5b-androstane-3b,17bdiol, 0.63% for 5b-dihydrotestosterone, 0.56% for androstenedione, 0.20% for epiandrosterone, and ,0.01% for all other
tested steroids (including male and female sex steroids and
their metabolites). Testosterone levels of the unknowns were
assigned by interpolation against a testosterone standard
curve. The lowest detectable level of testosterone in this RIA
was 0.025 ng/ml.
Statistical Analysis
The results are means 6 SE of each group (n 5 6 animals
sampled/group). One-way analysis of variance on the rank
(for testosterone plasma level) and Student-Newman-Keuls
methods were employed to determine the significance of the
differences between experimental means. A value of P , 0.05
was considered significant.
RESULTS
Cytokine Release by Peritoneal Macrophages
IL-1. Both sham-operated groups and animals in the
trauma-hemorrhage group with prior castration showed
comparable levels of peritoneal macrophage IL-1 release, as opposed to significantly depressed IL-1 release
in sham-castrated animals after trauma-hemorrhage
(253.8% compared with corresponding shams; P ,
0.05; Fig. 1A).
IL-6. Peritoneal macrophages from sham-operated
animals and castrated mice after trauma-hemorrhage
Fig. 1. A: release of interleukin-1 (IL-1) by peritoneal macrophages
harvested from castrated/sham-castrated male C3H/HeN mice at 24
h after initiation of experiment, in presence of 10 µg/ml lipopolysaccharide W (LPS). Cytokine levels were detected by specific bioassay
(D10.G4.1) for IL-1. Sham, control; Trauma-HEM: soft tissue trauma
1 hemorrhage; n 5 6/group # P , 0.05 vs. sham-operated animals;
1 P , 0.05 vs. corresponding castrated animals. B: release of IL-6 by
peritoneal macrophages harvested from castrated/sham-castrated
male C3H/HeN mice at 24 h after initiation of experiment, in
presence of 10 µg/ml LPS. Cytokine levels were detected by a specific
bioassay (7TD1) for IL-6. Sham, control; Trauma-HEM, soft tissue
trauma 1 hemorrhage; n 5 6/group. # P , 0.05 vs. sham-operated
animals; 1 P , 0.05 vs. corresponding castrated animals.
were found to release similar levels of IL-6 (Fig. 1B).
Sham-castrated mice showed significant depression of
IL-6 release after trauma-hemorrhage (P , 0.05) compared with the corresponding shams (Fig. 1B).
Cytokine Release by Splenic Macrophages
IL-1. Castrated animals after trauma-hemorrhage
demonstrated levels of splenic macrophage IL-1 release
that were comparable with sham levels (Fig. 2A).
Splenic macrophages from sham-castrated mice after
trauma-hemorrhage showed significant depression of
IL-1 release (250.9% compared with the corresponding
shams; P , 0.05).
IL-6. Sham-operated mice as well as castrated mice
after trauma-hemorrhage were found to have similar
levels of splenic macrophage IL-6 release (Fig. 2B).
Sham-castrated mice after trauma-hemorrhage showed
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IL-1 release by peritoneal and splenic macrophages was
determined by adding serial dilutions of the supernatants to
D10.G4.1 cells (2 3 104 cells/well) in the presence of concanavalin A (2.5 µg/ml; Pharmacia, Piscataway, NJ) as previously
described (8). Proliferation of the D10.G4.1 cells was measured by [3H]thymidine incorporation.
IL-6 activity in culture supernatant was determined by the
amount of proliferation of the murine B cell hybridoma cell
line 7TD1, which only grows in the presence of IL-6 (11).
Serial dilutions of macrophage supernatants were added to
4 3 103 7TD1 cells/ml, and the cells were incubated for 72 h at
37°C in 5% CO2. For the last 4 h of incubation, 20 µl of a
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
solution (MTT; 5 mg/ml in RPMI 1640; Sigma Chemical, St.
Louis, MO) were added to each well (only viable cells incorporate MTT). The assay was stopped by aspiration of 150 µl of
supernatant from each well, with subsequent replacement by
150 µl of 10% sodium dodecyl sulfate solution in PBS (lauryl
sulfate; Sigma) to dissolve the dark blue formazan crystals.
With the use of an automated microplate reader (EL-311;
Bio-Tek Instruments, Winooski, VT), the light absorbance
was measured at 595 nm.
Cells for all populations were also incubated in parallel
without stimulant as a negative control. No significant lymphokine or cytokine release was detected in these cultures.
C1338
MALE SEX STEROIDS AND MACROPHAGE FUNCTION
(1223.6% compared with corresponding sham-operated animals).
Plasma Testosterone Levels
Castration of male mice 2 wk before initiation of
sham operation or trauma-hemorrhage reduced plasma
testosterone to levels undetectable with the RIA used in
the present study. Sham-castrated animals, on the
other hand, had detectable levels of testosterone, which
were not significantly different in sham-operated animals or animals undergoing trauma-hemorrhage
(0.51 6 0.29 and 0.35 6 0.27 ng/ml, respectively).
DISCUSSION
significant depression of IL-6 release from splenic
macrophages compared with the corresponding shamoperated animals (P , 0.05).
IL-6 Release by Kupffer Cells
Sham-operated mice as well as castrated mice after
trauma-hemorrhage were found to have comparable
levels of Kupffer cell IL-6 release (Fig. 3). A slight
increase in IL-6 release from Kupffer cells after traumahemorrhage in castrated animals was observed, which,
however, was not significantly different from IL-6 release by Kupffer cells from sham-operated animals.
Sham-castrated mice after trauma-hemorrhage were
found to have significantly higher levels of Kupffer cell
IL-6 release, compared with sham-operated animals
Fig. 3. Release of IL-6 by Kupffer cells harvested from castrated/shamcastrated male C3H/HeN mice at 24 h after initiation of experiment,
in presence of 10 µg/ml LPS. Cytokine levels were detected by a
specific bioassay (7TD1) for IL-6. Sham, control; Trauma-HEM, soft
tissue trauma 1 hemorrhage; n 5 4/group. # P , 0.05 vs. shamoperated animals; 1 P , 0.05 vs. corresponding castrated animals.
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Fig. 2. A: release of IL-1 by splenic macrophages harvested from
castrated/sham-castrated male C3H/HeN mice at 24 h after initiation
of experiment, in presence of 10 µg/ml LPS. Cytokine levels were
detected by specific bioassay (D10.G4.1) for IL-1. Sham, control;
Trauma-HEM, soft tissue trauma 1 hemorrhage; n 5 6/group. # P ,
0.05 vs. sham-operated animals; 1 P , 0.05 vs. corresponding
castrated animals. B: release of IL-6 by splenic macrophages harvested from castrated/sham-castrated male C3H/HeN mice at 24 h
after initiation of experiment, in presence of 10 µg/ml LPS. Cytokine
levels were detected by a specific bioassay (7TD1) for IL-6. Sham,
control; Trauma-HEM, soft tissue trauma 1 hemorrhage; n 5
6/group. # P , 0.05 vs. sham-operated animals; 1 P , 0.05 vs.
corresponding castrated animals.
It has been suggested that the sexual dimorphism of
immune function in humans and animals is a result of
the effects of gonadal steroid hormones (9). Female
immune function during the proestrus and diestrus
state has been found to be unchanged or stimulated
following adverse circulatory conditions, as opposed to
significant depression of immune functions in male
mice after hemorrhagic shock (25, 27). In addition,
survival in a polymicrobial sepsis model was significantly higher in proestrus female than in male mice
(29). Thus it appears that female sex steroids may
contribute to this sexual dimorphism. Alternatively,
clinical observations and experimental studies also
suggest an important suppressive effect of male sex
steroids on immune functions (13, 17, 22, 23). Better
maintenance of female immunity may, therefore, be in
part due to the absence of immunodepressive androgenic hormones rather than the presence of physiological levels of estrogen or progesterone (13). The lack (or
low level) of androgens in females also alters the ratio
of androgen to estrogen, which is bound to sex hormone/
MALE SEX STEROIDS AND MACROPHAGE FUNCTION
blunted the systemic IL-6 release in blood. To the best
of our knowledge, the present study is the first to report
the protective effects of androgen deficiency on depressed peritoneal and splenic macrophage immune
functions seen following trauma-hemorrhage, as measured by the release of IL-1 and IL-6. In addition, the
suppression of the augmented release of the proinflammatory cytokine IL-6 from Kupffer cells after soft tissue
trauma and severe hypotension as observed here may
serve to protect the traumatized host from the sequelaeassociated systemic proinflammatory mediator release.
At 2 wk after castration, no detectable levels of
testosterone were present in the plasma of male C3H/
HeN mice when samples were obtained 24 h following
trauma-hemorrhage or sham operation (see RESULTS ).
Alternatively, in mice that were not castrated, although
testosterone levels between ,0.8 and 0.1 ng/ml plasma
were detectable, trauma-hemorrhage did not produce
any significant change in circulating testosterone levels
compared with sham. Nonetheless, significant immunological alterations were observed when comparing shamoperated animals and animals after trauma-hemorrhage. This suggests that the immunological changes
observed in the present study were not necessarily due
to increased levels of male sex steroids after traumahemorrhage but might be due to the presence of normal
physiological testosterone levels. We cannot, however,
preclude the possibility that testosterone levels could
have increased transiently during the hypotensive insult or within the initials hours following shock in the
sham-castrated animals, as this period was not assessed.
Although our results support the notion that male
sex steroids have immunosuppressive effects following
trauma-hemorrhage, the mechanism(s) of androgenic
suppression of the immune system is not known (23).
Thus it remains to be determined whether the beneficial effects of androgen-deficiency are due to the lack of
testosterone interaction with immunocompetent cells
or to the indirect effects of missing testosterone at
receptor sites in the central nervous system or in other
tissues. In addition, the present study cannot exclude
the possibility that other hormonal alterations due to
castration might also beneficially influence immune
functions following trauma-hemorrhage. However, our
preliminary studies indicate that administration of
flutamide, a testesterone receptor blocker (25 mg/kg
body wt sc) following tramua-hemorrhage in normal,
i.e., noncastrated animals also appears to restore the
depressed immune functions (unpublished observations). This would suggest that testosterone itself is
involved in producing immunodepression, since testosterone depletion (by surgical castration) or testosterone
receptor blockade prevented the immunodepression
following trauma-hemorrhage.
Previous studies have shown that maximal immune
suppression occurs within the 24-h period after hemorrhage, following which the immunological functions
gradually return to normal over a period of 5–7 days
(28). Because macrophage immune function was maintained at 24 h following trauma-hemorrhage by andro-
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testosterone binding globlin (13). Because this globlin
plays a key role in controlling the free plasma sex
hormone levels (both testosterone and estrogen), it may
also contribute to the effect castration had on hemorrhaged mouse immune responsiveness. However, the
role of this agent or its levels in plasma following
trauma-hemorrhage were not assessed in this study.
Castration studies in animal models of autoimmune
diseases have shown a potent protective role of androgens in suppressing the autoimmune disease process,
which indicates a significant depression and/or control
of the host immune system by androgens (for a review
see Ref. 13). Moreover, recent studies indicate protective effects of castration before soft tissue trauma and
hemorrhagic shock on splenocyte immune function, as
indicated by splenocyte proliferative capacity and IL-2
and IL-3 release (26).
Despite the available information concerning the
immunodepressive potential of male sex steroids on
different aspects of immune functions in normal conditions as well as in autoimmune diseases, it remains
unknown whether male sex steroids affect macrophage
immune function following soft tissue trauma and
severe hemorrhagic shock.
The results presented above clearly show that castration of male mice before the experiments maintains
macrophage immune function after trauma-hemorrhage. This is evidenced by the restoration of normal
levels of IL-1 and IL-6 release by peritoneal and splenic
macrophages in response to stimulation in castrated
mice, as opposed to significant depression of these
immunological parameters in sham-castrated male mice
after trauma-hemorrhage. Alternatively, IL-6 release
from Kupffer cells was found to be significantly increased in sham-castrated mice after trauma-hemorrhage, whereas castrated mice after trauma-hemorrhage showed IL-6 release comparable with shamoperated mice. These observations of differential
macrophage responsiveness seen following hemorrhage are in keeping with our earlier findings (3). The
nature of the differential response of macrophage from
the peritoneum and spleen (depressed inducible cytokine release) as opposed to Kupffer cells (augmented
cytokine release) to exogenous stimulation appears to
exist at a posttranscriptional level. This conclusion is
based on our finding that macrophages obtained from
all these tissue sites from hemorrhaged mice showed
augmented cytokine mRNA expression in response to
in vitro stimulation but not increased protein release
(30). The actual nature of the translation and/or posttranslational block remains to be determined and is
beyond the aim and scope of this study. Nonetheless,
Kupffer cells are recognized to play an important role in
the mediation of the systemic inflammatory response
after trauma-hemorrhage (3, 16), and thus it was
important to compare the responses of these varied
macrophage populations. To the extent that this augmented Kupffer cell capacity to release IL-6 accounts
for the rise in proinflammatory cytokine seen following
hemorrhage, studies by O’Neill et al. (16) demonstrated
that Kupffer cell depletion before hypotensive shock
C1339
C1340
MALE SEX STEROIDS AND MACROPHAGE FUNCTION
This work was supported by National Institute of General Medical
Sciences Grant R01-GM-37127.
A preliminary account of this work was presented at the 77th
Annual Meeting of the New England Surgical Society in Dixville
Notch, NH, September 29, 1996.
Present address of M. W. Wichmann: Ludwig-Maximilians Univ.,
Klinikum Grosshadern, Dept. of Surgery, Marchioninistrasse 15,
81377 Munich, Germany.
Address for reprint requests: I. H. Chaudry, Center for Surgical
Research, Middle House II, Brown Univ. School of Medicine and
Rhode Island Hospital, 593 Eddy St., Providence, RI 02903.
Received 3 February 1997; accepted in final form 27 June 1997.
12.
13.
14.
15.
16.
17.
18.
19.
20.
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gen depletion, it appears likely that normal immunological responses would be maintained at time points
beyond the one used in this study. The present results,
based on the measurement of macrophage immune
function, therefore, indicate deleterious effects of male
sex steroids on immune function after soft tissue trauma
and severe hemorrhage. Short-term treatment with
testosterone-blocking agents instead of castration following trauma-hemorrhage could therefore be a useful
adjunct for maintaining host immune function under
those conditions. Additional studies are, however,
needed to demonstrate whether pharmacological testosterone antagonism/depletion following soft tissue
trauma and severe hemorrhage with agents such as
leuprolide and/or flutamide can provide any beneficial
effects on immunity in these situations and by what
mechanism they may act on these cells.