T cell immunology Kim Min Sung

Abstract  Introduction  T cell receptor, TCR  T cell accessory molecules

Introduction

The kind of a T cell. T cell typeCo-receptorMHC restrictionFunction Helper T cellCD4ClassB cell help Macrophage activation Help for CD8 T cells Cytokine secretion Cytotoxic T cellCD8ClassKilling virus infected cells

The facility of a T cell.

a CD8 T cell with a CD4 t cell.

MHC resrtiction  MHC : major histocompatibility complex  T cell can recognize necessarily the antigen through MHC molecule and recognizes the part of the antigen.

T cell Receptor, TCR

T cell receptor  TCR : Antigen awareness acceptor in T cell surface. Consist of αβ T cell receptor that is consisted of α and β chain and part consists of γδ T cell receptor that is consisted of γ and δ chain.  αβ T cell receptor : Have been revealed in most peripheral T cell and is limited by MHC.  γδ T cell receptor : Only, it is special kind of T cell that it is known as that have been revealed in tip of a twig blood T cell of decimal and is not limited by MHC.

αβ T cell receptor  α, β chain two proteins are achieved gathering, these two protein chains each other cavalent bond being done in cell membrane exist.  α chain : Cell membrane protein that have about 40 ~ 50 KDa's molecular weight by acidic glycoprotein.  β chain : Cell membrane protein that have about 40 ~ 45 KDa's molecular weight by neuter gender or basic glycoprotein.  α, β chain is accomplishing CD3 protein and complex in cell membrane, call that is CD3-TCR complex usually.

γδ T cell receptor  γδ TCR appear, and is revealed in particular peripheral T cell of decimal which do not reveal αβ TCR also in ripening immature thymocyte.  Revelation in T cell of particular area such as intraepithelial lymphocyter (T cell in head's mucosa) or dendritic epidermal cells (T cell in cuticle formation)  Confirmation that recognize PPD (purified protein derivatives) of tuberculosis germs or heat shock protein  Is thought if is resemblant with NK cell that destroy cancerous cells, or do not act on cell that remove cell that is damaged by inflammation effect.

Solid structure of TCR and MHC  Upper direction is TCR, and down is MHC.  Part that color paints in picture is part that TCR and MHC do interaction directly.

CD3-TCR complex

T cell accessory molecules

 Is low comparatively than union protein plain that TCR's antigen affinity is different including antibody.  Coherence between TCR and MHC-peptide complex is not enough to stimulate T cell in antigen awareness through TCR.  T cell's antigen awareness need union between other molecules that make their coherence durably to TCR except.  CD2, CD4, CD8, LFA-1 protein etc. are representative accessory molecules

T cell accessory molecules

CD4, CD8  CD4 : · Glycoprotein in cell membrane about 55 kDa. · In Leu3 or T4, mouse in a person L3T4. Person's CD4 is acceptor of HIV virus. · CD4 is union to class II MHC's non-polymorphic region.  CD8 : · Glycoprotein that is combined in cell membrane that is consisted of α and β relationship two proteins. · In Leu2 or T8, mouse in a person Lyt-2/Lyt-3. · CD8 is union to class I MHC's non-polymorphic region.

Other accessory molecules  CD2 : Is called that is T11, LFA-2, Leu5, SRBC receptor by membrane glycoprotein. Ligand is LFA-3 or CD58. Function as signal transducing molecules.  LFA-1 (lymphocyte function-associated antigen-1) : Cell union protein (adhesion molecule) belonging to integrin family. Ligand is ICAM-1 and ICAM-2.  Other accessory molecules : CD28, CD44, CD45, CD5, Thy-1, Ly-6