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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