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Immunologiskt minne.
Kursbok: ”The immune system” Peter Parham
Kapitel 8.21-8.25
•Immunological memory: ability of the immune system to respond more
rapidly and effectively to pathogens that have been encountered previously.
•Pre-existence of a clonally expanded population of antigen-specific
lymphocytes. Secondary, tertiary, and so on … memory responses also
differ in the quality from the primary response. For example, the
characteristics of antibodies produced in secondary and subsequent
responses are distinct from those produced in the primary response to the
same antigen.
•It is still not clear today if memory reflects a long-lived population of
specialized memory cells or depends on the persistence of undetectable
levels of antigen that continuously re-stimulate antigen-specific
lymphocytes.
2 possibilities:
a) memory is sustained by long-lived lymphocytes, induced by the original
exposure, that persist in a resting state until a new encounter with the
same pathogen.
b) Lymphocytes originally activated by the pathogen are repeatedly
re-stimulated, even in the absence of re-infection with the pathogen.
• Pathogen subsists in a small amount so as to not have the capacity to
induce a new infection, but still can re-stimulate the activated lymphocytes.
This re-stimulation could occur via the follicular dendritic cells.
•
Specific cytokines could mediate re-stimulation.
Tydliga skillnader mellan naiva och minne B celler:
T minnesceller identifieras lättast genom att kolla vissa förändringar på
ytan.
CD45RO som finns på minnesceller binder
mycket bättre till TCR/CD3 komplex och gör
så att den överförda signalen kommer fram
mycket mera effektivt på ett minnescell än
på en naiv cell.
Antibody can suppress naiv B cell activation by crosslinking
the B-cell antigen receptor
Det är ju direkt onödigt att sätta igång med en helt ny process när man
kan få effektiva och snabba svar med minnesceller.
ITIM
Preexisting
soluble
antibody
Immune complexes bound to follicular dendritic cells (FDC) form
ICCOSOMES. Antigen can persist in this form for long periods.
3 faser i immunsvaret