Immunity

Objectives List B Lymphocytes Marker Discuss T cell dependent Ag Define T cell independent Ag Enumerate Natural Killer cell Markers Mention the Functions of NK cell Show the link between NK cells & innate immunity Define LAK cell

B lymphocyte 15-35% of total lymphocytes pre B cell Intra cytoplasmic chain Immature B surface IgM Mature B surface IgM +IgD Activation plasma cell secrete Ig memory cell

B


Surface marker Receptor& Mol Receptor FCR C3b R(CD35)

Mol =B7 Class I & II MHC Sp. Marker CD 19, 20,21 B cell secrete IL1 ,IL6


B lymphocytes : (activation) T cell dependent Ag (majority) B cell can not be activated effectively in the absence of assistance from Th2 cell (help by secreting of cytokine)(Th2 IL4.IL5,IL6) B cell need 2 signals: 1-Recognition of Ag & present it to T cell in ass. with class 2 to activate T cell 2-Interaction of CD40 with CD40L then B cells begin to Express receptors for various cytokines

Humoral Response to T Dependent Antigens

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IL 4,5,6



T cell independent Ag (TI) TI-1: like bacterial lipopolysaccharid, E.B. virus Inherited mitogenic activity have a Receptor on B cells . activation many B lym.= poly colonel B cell activation TI-2:like pneumococcal polysacch. These Ag have multiple repeats of their epitope & cross link numerous Ag receptors on B cell surface IgM only no memory cells

Receptors

Natural Killer cell Specific Marker CD 56+ve CD3-ve Non T non B large granular lymphocyte Not present at early & old ages so increase risk of cancer at those ages Kills in a non specific (innate immunity) non MHC restriction not needs sensitization not needs APC no memory so belong to non specific immunity.

NK cells cytotoxic for tumor cells, viral infected cell ,also for some bacteria ,fungal, ¶sitic infectionMode of killing is by ADCC (Ab dependent cell cytoxicity)(R eceptor no. CD 16)for FC of IgG Activated by gamma IFN (γ IFN) , IL2,IL12 LAK cells (NK +gamma IFN, IL2) Lymphocyte activated killer

*Perforating cell memb. by inserting perforin= Into cell memb. Polymerize Polyperforin channel *Protease =degrade prot. in cell memb. *Nuclease=degrade N.A. *TNF=prevent protein synthesis . Produce toxic free radical

Natural killer cells which rid the body of pre-cancerous tissues characterized by; a-need antigen presenting cells for activation b-CD56 is the specific marker for their identification c-Needs Class II HLA for its activation d-Belongs to the Specific immunity


Natural killer cells which rid the body of pre-cancerous tissues characterized by; a-need antigen presenting cells for activation b-CD56 is the specific marker for their identification c-Needs Class II HLA for its activation d-Belongs to the Specific immunity