Download Development of B Lymphocytes

THE DEVELOPMENT OF
B-LYMPHOCYTES
STAGES IN LIFE CYCLE OF
B-LYMPHOCYTES
* Stage 1
* Maturation in bone marrow with development of
functional receptors
* Stage 2
* Testing for and elimination of self-reactive receptors
* Stage 3
* Mature naïve cells move to secondary lymphoid tissues
* Stage 4
* Antigen contact with differentiation into plasma cells
and memory cells
B-CELL DEVELOPMENT IN BONE
MARROW
* Stages are defined by rearrangement and expression
of IG genes
* Early Pro-B cells
* Earliest cells in B-cell lineage
* Rearrangement of variable domain of heavy chains
* D to J
* Late Pro-B cell
* Rearrangement of variable domain of heavy chains
* V to DJ
B-CELL DEVELOPMENT IN BONE
MARROW
* Large Pre-B cell
* M expressed on cell surface along with surrogate light
chains and signal transduction molecules
* Pre-B cell receptor
* Small Pre-B cell
* Pre-B cell receptor not present
* Most M chains inside cell
* Light chain rearrangement begins
B-CELL DEVELOPMENT IN BONE
MARROW
* Immature B-cell
* Heavy and light chains assembled and transported to
surface as IgM receptor complex
* Randomness of gene rearrangements leads to selfreactive B-cells
* Mature B-cell
* IgD expressed on cell surface
* Called naïve B-cells
Figure 4-4
B-CELL DEVELOPMENT IN BONE
MARROW
* Development depends on non-lymphoid stromal cells
* Function of stromal cells
* Specific contact through cell adhesion molecules (CAM’s)
* VCAM-1 to VLA-4 on early pro-B cells
* Produce growth factors for bound B-cells
* Stem cell factor (SCF)
* Interleukin-7 (IL-7)
* Growth factors
* Stem cell factor stimulates (G/P) of Early pro-B cells
* Interleukin-7 stimulates (G/P) of Late pro-B and L/S pre-B cells
GENE REARRANGEMENTS AND BCELL SURVIVAL
* Gene rearrangement process is imprecise and classified as
* Unproductive
* Not translated into IG chain
* B-cell dies
* Productive
* Translated into IG chain
* Development proceeds
* Immunoglobulin loci
* Each B-cell has 2 copies on homologous chromosomes
* Rearrangements made on both
PROTEINS INVOLVED IN
REARRANGEMENT AND EXPRESSION
OF IG GENES
* Several categories of specialized proteins are required
* Lymphoid specific recombination
* RAG-1 and RAG-2
* N-nucleotide addition
* TdT
* Surrogate light chains
* Lambda5 and VpreB
* Signal transduction
* IG-alpha, IG-beta, CD45 and Btk
* Transcription factors
* EBF and Oct-2
SIGNAL TRANSDUCTION AND
BRUTON’S TYROSINE KINASE (BTK)
* Bruton’s tyrosine kinase (Btk)
* Encoded by gene on X chromosome
* Essential for B cell maturation
* Mutation in gene
* B cells maturation stops at pre-B cell stage
* Results in immunodeficiency called
* Bruton’s X-linked agammaglobulinemia
* Immunodeficiency results in recurrent sinopulmonary
infections with
* Streptococcus pneumoniae
* Haemophilus influenzae
POPULATIONS (SUBSETS) OF B CELLS
* B-1 cells (minor subset)
*
*
*
*
*
Develop early in embryonic life with unknown origin
Express CD5 (CD5 B cells)
Self-renewing
Primary location is body cavities (pleural / peritoneal)
Produce polyspecific antibodies
* B-2 cells (major subset)
*
*
*
*
*
Develop after birth
Do not express CD5 glycoprotein
Replaced from bone marrow
Primary location is lymphoid organs
Produce highly specific antibodies
NEGATIVE SELECTION AND FURTHER
DEVELOPMENT OF B CELLS
* Self reactive immature B cells are either
* Eliminated or inactivated
* IgM receptor may react with
* Cell surface or soluble self antigens
* Reactions with cell surface antigens
* Induced to commit suicide by apotosis
* Clonal deletion
* Reactions with soluble antigens
* Rendered unresponsive (anergic) to antigen
* Maturation continues with reduced surface IgM
SELECTION AND FURTHER
DEVELOPMENT OF B CELLS
* B cells leave bone marrow and circulate between blood
and secondary lymphoid tissues
* Secondary lymphoid tissue contains primary lymphoid
follicles
* Primary lymphoid follicle
* Area where B cells congregate in association with specialized
stromal cells (follicular dendritic cells)
* Passage through primary lymphoid follicle and contact
with follicular dendritic cells (FDC) necessary for survival
* Few days with no passage
* 3 to 8 weeks with passage
CIRCULATION OF B CELLS THROUGH
SECONDARY LYMPHOID TISSUES
(LYMPH NODES)
* Chemokines attract B cells to leave blood and enter cortex
of lymph node via high endothelial venule (HEV)
* Chemokines attract B cells to lymph node and primary
lymphoid follicle
* No encounter with antigen
* B cells leave node via efferent lymphatic vessel
* Anergic B cells detained in T cell area
* Induced to commit suicide by apoptosis
B CELL ENCOUNTER WITH ANTIGEN IN
SECONDARY LYMPHOID TISSUES
* Encounter with antigen takes place in T cell area of lymph
node cortex
* Antigen reached lymph node from infected tissue via
afferent lymphatic vessel
* B cell is activated by CD4 T-cell in T-cell area
* Activated B cells
* Migrate to medulla area and differentiate into plasma cells
* Migrate to primary follicle to form germinal center
* Migrate to medulla or bone marrow and complete differentiation into
plasma cells
* Develop into memory B cells
B-LYMPHOCYTE TUMORS
* Caused by mutations in genes that regulate cell growth
* Genes regulating cell growth
* Proto-oncogenes
* Promotes cell growth
* Tumor suppressor genes
* Inhibits cells growth
* Mutations in growth regulating genes
* Transformation into oncogenes (cancer causing genes)
B LYMPHOCYTE TUMORS
* Represents uncontrolled growth of single transformed B
cell
* Associated with all stages of development
* Tumors retain characteristics of cell type and location
* Hodgkin’s Lymphoma
* Germinal center B cell in lymphoid tissue
* Multiple myeloma
* Plasma cell in bone marrow
* Waldenstrom’s macroglobulinemia
* IgM secreting B lymphocyte in lymphoid tissue
* Burkitt’s lymphoma
* Resembles germinal center B cell in lymphoid tissue
Figure 4-19
HODGKIN’S DISEASE (LYMPHOMA)
* Hodgkin’s disease is a type of lymphoma
* Two types of lymphoma
* Hodgkin’s disease
* Non-Hodgkin’s lymphoma (NHL)
* Two main types of Hodgkin’s disease
* Classical (95%)
* Nodular lymphocyte predominance (5%)
* Disease most often starts in lymph nodes of upper body
* Chest, neck or under the arms
HODGKIN’S DISEASE (LYMPHOMA)
* Cause is not known but there are risk factors
* Epstein-Barr Virus (EBV) infection
* Geography
* United States, Canada, northern Europe
* Family history
* Identical twin (very high)
* Approximately 8,000 new cases each year in US
* Cancer cells of HD are unique
* Reed-Sternberg cells
WALDENSTROM’S
MACROGLOBULINEMIA
* Indolent, non-Hodgkin’s lymphoma (NHL)
* Classified as
* Monoclonal gammopathy
* Cancer cells
* Features of B-cells and plasma cells
* Lymphoplasmacytoid
* Located primarily in bone marrow
* Produce large amounts of monoclonal protein (antibody)
* IgM
* Approximately 1,500 new cases each year in US
MULTIPLE MYELOMA
* Aggressive, non-Hodgkin lymphoma
* Classified as
* Monoclonal gammopathy
* Cancer cells
* Abnormal plasma cells (myeloma cells)
* Located primarily in bone marrow
* Produce monoclonal proteins (antibody)
* IgG, IgA, free kappa or lambda light chains
* Approximately 20,000 cases in US for 2008
BURKITT’S LYMPHOMA
* B cell tumor with 2 forms
* Endemic (African)
* Facial tumors
* Strongly associated with EBV infection
* Nonendemic (Sporadic)
* Abdominal tumors
* Characteristic translocation
* MYC proto-oncogene on chromosome 8 to IG genes
* Chromosome 14 (90%)
* Chromosomes 2 and 22 (10%)
* MYC protein
* Normally regulates cell division
* Control is lost following translocation to IG gene
CASE STUDY – 21 YEAR OLD MALE
* 21 year old WM presents with
*
*
*
*
Fever (102 F)
Sore throat
Moderate malaise, myalgia and fatigue
Difficulty in swallowing
* H and P
*
*
*
*
Healthy and sexually active
Bilateral anterior and posterior cervical lymphadenopathy
Pharyngeal inflammation
Mild splenomegaly and no jaundice
CASE STUDY – 21 YEAR OLD MALE
* Admitted to MC and administered
* Penicillin G
* Prednisone
* Valacyclovir
* Laboratory tests
*
*
*
*
*
CBC with diff
Liver function tests
Monospot test (Heterophile antibody)
Erythrocyte sedimentation rate (ESR)
Group A streptococcus antigen
CASE STUDY – 21 YEAR OLD MALE
* CBC with diff
*
*
*
*
*
WBC
RBC
Platelets
Hemoglobin
Hematocrit
*
*
*
*
Neutrophils
Lymphocytes
Atypical lymphocytes
Monocytes
12.5
4.0
250
14.0
40
[4.8-10.8]
[3.93-5.22]
[150-450]
[11.2-15.7]
[34.1-44.9]
K/uL
M/uL
K/uL
g/dL
%
45
55
18
12
[40-74]
[15-47]
%
%
%
%
[0-12]
REACTIVE (ATYPICAL)
LYMPHOCYTES
* Larger in size
* Up to 30 um in diameter
*
*
*
*
*
More cytoplasm
Less dense nuclear chromatin
Irregular shaped nucleus
Nucleous may be present
Periphery of cell show “scalloped edge”
CASE STUDY – 21 YEAR OLD MALE
* Liver function tests
* ALT
* AST
* Alk phos
* ESR
130
112
150
40
[19-55] U/L
[15-37] U/L
[50-136] U/L
[0-30]
mm/hr
* GAS antigen
Negative
[Negative]
* Monospot test
Positive
[Negative]
CASE STUDY – 21 YEAR OLD MALE
* Patient discharged after 36 hours
* Treatment
* NSAID
* Recommendations
* Avoid sports
* Avoid alcohol
CASE STUDY – 18 YEAR OLD FEMALE
* 18 year old HF presents with
*
*
*
*
Fever (101 F)
Sore throat
Moderate malaise, myalgia and fatigue
Difficulty in swallowing
* H and P
*
*
*
*
Healthy and sexually active
Bilateral anterior and posterior cervical lymphadenopathy
Pharyngeal inflammation
Mild splenomegaly and no jaundice
CASE STUDY – 18 YEAR OLD FEMALE
* Admitted to MC and administered
* Penicillin G
* Prednisone
* Valacyclovir
* Laboratory tests
*
*
*
*
*
CBC with diff
Liver function tests
Monospot test (Heterophile antibody)
Erythrocyte sedimentation rate (ESR)
Group A streptococcus antigen
CASE STUDY – 18 YEAR OLD FEMALE
* CBC with diff
*
*
*
*
*
WBC
RBC
Platelets
Hemoglobin
Hematocrit
*
*
*
*
Neutrophils
Lymphocytes
Atypical lymphocytes
Monocytes
13.5
4.2
260
14.5
42
[4.8-10.8]
[3.93-5.22]
[150-450]
[11.2-15.7]
[34.1-44.9]
K/uL
M/uL
K/uL
g/dL
%
46
56
20
12
[40-74]
[15-47]
%
%
%
%
[0-12]
CASE STUDY – 18 YEAR OLD FEMALE
* Liver function tests
* ALT
* AST
* Alk phos
* ESR
136
115
156
42
[19-55] U/L
[15-37] U/L
[50-136] U/L
[0-30]
mm/hr
* GAS antigen
Negative
[Negative]
* Monospot test
Negative
[Negative]
CASE STUDY – 18 YEAR OLD FEMALE
* Epstein-Barr Virus serology (IFA)
*
*
*
*
*
Viral capsid antigen (VCA) IgM
Viral capsid antigen (VCA) IgG
Early antigen (D + R) IgG
Nuclear antigen (NA) IgM
Nuclear antigen (NA) IgG
1:320
1:40
1:20
1:80
< 1:10
[< 1:20]
[< 1:10]
[< 1:10]
[< 1:10]
[< 1:10]
CASE STUDY – 18 YEAR OLD FEMALE
* Patient discharged after 24 hours
* Treatment
* NSAID
* Recommendations
* Avoid sports
* Avoid alcohol
CASE STUDY – 24 YEAR OLD FEMALE
* 24 year old WF presents with
*
*
*
*
Fever (101 F)
Moderate malaise and fatigue
Myalgia and bone pain
Shortness of breath
* H and P
*
*
*
*
No significant history
Generalized lymphadenopathy
Pallor
Mild splenomegaly and no jaundice
CASE STUDY – 24 YEAR OLD FEMALE
* Admitted to MC with diagnosis of
* Pneumonia and anemia
* Laboratory tests
*
*
*
*
CBC with diff
Monospot test (Heterophile antibody)
Pregnancy test
Influenza A and B antigens
CASE STUDY – 24 YEAR OLD FEMALE
* CBC with diff
*
*
*
*
*
WBC
RBC
Platelets
Hemoglobin
Hematocrit
*
*
*
*
*
Neutrophils
Lymphocytes
Atypical lymphocytes
Monocytes
Blasts
44.4
1.0
8
3.6
11.3
6
10
0
20
55
[4.8-10.8]
[3.93-5.22]
[150-450]
[11.2-15.7]
[34.1-44.9]
[40-74]
[15-47]
[0-12]
K/uL
M/uL
K/uL
g/dL
%
%
%
%
%
%
CASE STUDY – 24 YEAR OLD FEMALE
* Pregnancy test
Negative
[Negative]
* Influenza antigens
Negative
[Negative]
* Monospot test
Positive
[Negative]
* Peripheral blood smear
* RBCs showing anisopoikocytosis. Leukocytes show predominance of
blasts many with cytoplasmic granules. Mature granulocytes show
dysplastic features. Monocytes are atypical.
CASE STUDY – 20 YEAR OLD
FEMALE
* 20 year old WF presents to ED c/o
* Chest pain
* POCT
* Troponin
* CK MB
* CK, Total
23.21
44.8
611
[< 0.7]
[< 3.6]
[21 – 215]
ng/mL
ng/mL
U/L
* Admitted to MC with diagnosis of
* STEMI (ST segment elevation myocardial infarction)
* Transported to Cardiac Catheterization Laboratory
CASE STUDY – 20 YEAR OLD
FEMALE
* History and Physical
* Leg and hip pain 1 day prior
* Diagnosis of IM 1 month prior
* CBC with DIFF
*
*
*
*
*
*
WBC
RBC
Platelets
Neutrophils
Lymphocytes
Monocytes
8.6
3.86
179
66
24
10
[4.8-10.8]
[4.00-5.40]
[145-400]
[40-74]
[15-47]
[0-12]
K/uL
M/uL
K/uL
%
%
%
CASE STUDY – 20 YEAR OLD
FEMALE
* Cardiac catheterization
* Blockage of left anterior descending artery
CASE STUDY – 20 YEAR OLD
FEMALE
* Lipid profile
*
*
*
*
Cholesterol
HDL
LDL
Triglycerides
134
42
74
90
[< 200] mg/dL
[> 40] mg/dL
[< 130] mg/dL
[< 200] mg/dL
* Homocysteine
5.6
[< 10.4]
umol/L
* Lipoprotein(a)
15
[< 75]
mg/dL
* Cardiolipin antibody
Positive
[Negative]
CASE STUDY – 20 YEAR OLD
FEMALE
* Mononucleosis test
* Positive (strong)
* EBV early antigen, IgG
* Negative
* CBC with DIFF
* Normal