MEMBRANE RECEPTOR FOR ANTIGEN Kelompok : 4 Ninda Sahriyani ( ) Ganys Tri S. ( ) Agatha Mia( ) Vita Agustina( ) Jurusan Biologi Fakultas Matematika dan Ilmu pengetahuan Alam Universitas Brawijaya 2013

THREE LIMBS OF IMMUNE RESPONE Fig 1. Three Limbs Immune Respone

Group of genes that code for proteins that found on the surfaces of cells that help the immune system recognize foreign substances Also known as HLA (Human Leukocyte Antigen) Two types: Class I Found in every nucleated cell Bound to cytotoxic T cell (CD8) Class II Found in special cell such as macrophage, dendritic cell, B cell, and thymus Bound to Helper T cell Major Histocompatability Complex (MHC)

1.Determinate between the self and nonself antigens 2.Presenting antigen to T cells 3.Determinate interaction between B cells, T cells and other cells. Function of MHC

There are 3 ways of processing and presentation antigens : 1.Protein from extracellular pathogen broken down and processed by exogen pathway 2.Protein from self-protein and virus protein processed by endogen pathway 3.Lipid and derivate processed like extracelular protein and endosom, with CD1, that similiar to MHC and presented to CD8 T cell. Function of MHC Degradation Process (Processing and Presentation) Antigen

Fig 2. MHC Structures

TABLE 1. DIFFERENCES BETWEEN CLASS I AND CLASS II MHC VariableClass I MHCClass II MHC Bound toCD8 T cellCD4 T cell Enzyme to form peptide Cytosolic proteaseEndosome and lysosom protease Peptide binding site in cell Reticulum endoplasmicVesicle specialized compartment Peptide size8-9 amino acid13-17 amino acid Expression and Presentation Expressed to hematopoietic cells Presented by all nucleated cells. Expressed to hematopoietic cell and stromal cell at thymus Presented by macrophage, dendritic cell, B cell

SIMILARITIES OF ANTIGEN PRESENTING BY MHC MOLECULES Presented to T cell on the surface of APC (Antigen Presenting Cell) Every MHC can only bind to single antigen fragment at one time, at the peptide binding cleft The presented antigen fragment is only amino acid chain The binding is done intracellular

Fig 2. Class I MHC Antigen Presenting Pathway

Fig 3. Class II MHC Antigen Presenting Pathway

T Mature T cell have thousands identical receptor on the cell surface 2 kinds of receptor: – Alpha/beta (αβ) chain T cell (95%) – Gamma/delta (γδ) chain T cell (5%) Co-receptor : CD4 and CD8 Mature T cell have thousands identical receptor on the cell surface 2 kinds of receptor: – Alpha/beta (αβ) chain T cell (95%) – Gamma/delta (γδ) chain T cell (5%) Co-receptor : CD4 and CD8 T Cell Receptor (TCR)

Fig 5. TCR-CD3 TCR binding to MHC-antigen The long cytoplasmic tail of the CD3 functions in signal transduction. T Cell Receptor Complex: TCR-CD3

Fig. 6 Role of co- receptor CD 4 and CD8 : they may act as adhesion molecule helping the T cell bind to the APC during antigen presentation for duration that is sufficient for antigen recognition or act as signal transducers. Role of co-receptors in TCR binding affinity

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VIDEO Link : T Cell Dependent Antigens 110/micro33.swf Cytotoxic T Cell hill.com/olc/dl/120110/micro34.swf