Class II MHC

Peptides are bound differently by class I and class II MHC molecules... 

Class 1 and class II MHC molecules bind peptide antigens and present them at the cell surface for interaction with receptors on T cells. The extracellular portion of these molecules consists of a peptide-binding domain formed by two helical regions on top of an eight-stranded antiparallel p sheet, separated from the membrane by two lower domains with immunoglobulin folds. These domains are differently disposed between the two protein subunits in class I and class II molecules. 

Murthy, V.L., 5tern, L.J. The class II MHC protein HLA-Drl in complex with an endogenous peptide implications for the structural basis of the specificity of peptide binding. Structure 5 1385-1396, 1997. 

ANAb Anti-nuclear antibodies ANCA Anti-neutrophil cytoplasmic auto antibodies cANCA Cytoplasmic ANCA pANCA Perinuclear ANCA AND Anaphylactic degranulation ANF Atrial natriuretic factor ANP Atrial natriuretic peptide Anti-I-A, Anti-I-E Antibody against class II MHC molecule encoded by I-A locus, I-E locus, anti-lg Antibody against an immunoglobulin... 

Most transformed cells do not express class II MHC molecules and express lower than normal levels of class I MHC molecules. This renders their detection by immune effector cells more difficult. Treatment with cytokines, such as IFN-y, can induce increased class I MHC expression, which normally promotes increased tumour cell susceptibility to immune destruction. 

Hammerberg, C., Duraiswamy, N., and Cooper, K. D., Temporal correlation between UV radiation locally-inducible tolerance and the sequential appearance of dermal, then epidermal, class II MHC+ CDllb+ monocytic/macrophagic cells, J. Invest. Dermatol. 107, 755-763, 1996. 

Engelhard, V.H. (1994) Structure of peptides associated with class I and class II MHC molecules. Annu. Rev. Immunol. 12, 181-207. 

Communication requires a signal and a signal receiver. Signal receivers are termed receptors. We have seen two examples the antigen-specific receptors on B cells and the receptors on T cells which recognize Class II MHC processed antigen complexes on the surface of B cells, two more examples of molecular recognition. 

Class II MHC proteins also consist of two peptide chains, which are related to each other. MHC 11 molecules are found on all anti-gen-presenting cells in the immune system. They serve for interaction between these cells and CD4-carrying T helper cells. 

Hughes, A., Brock, J. H., Parrott, D. M., and Cockbum, F. (1988). The interaction of infant formula with macrophages Effect on phagocytic activity, relationship to expression of class II MHC antigen and survival of orally administered macrophages in the neonatal gut. Immunology 64, 213-218. 

X, Ig receptor V, class II MHC antigen receptor o, peptide from degraded foreign antigen T cell receptor ... 

Inappropriate expression of class II MHC molecules on the membranes of cells that normally do not express class II MHC (eg, islet beta cells). Increased expression of MHC II may increase presentation of self peptides to T helper cells, which in turn induce CTL, TDTH, and B-lymphocyte cells that react against self antigens. 

These proteins consist of a and /3 chains, (a) In class I MHC proteins, the small /3 chain is invariant but the amino acid sequence of the a chain exhibits a high degree of variability, localized in specific domains of the protein that appear on the outside of the cell. Each human produces up to six different a chains for class I MHC proteins, (b) In class II MHC proteins, both the a and /3 chains have regions of relatively high variability near their amino-terminal ends. 

Class II MHC proteins occur on the surfaces of a few types of specialized cells, including macrophages and B lymphocytes that take up foreign antigens. Like class I MHC proteins, the class II proteins are highly polymorphic, with many variants in the human popula-... 

Some very hydrophobic antigens are presented by neither a class I nor a class II MHC molecule but by members of the CD1 family, leukocyte surface proteins that are not encoded in the MHC gene region.266 271 272... 

The two classes of MHC proteins are displayed on different cell types. Class I MHC proteins are found on almost all nucleated cells, including killer T cells. Class II MHC proteins are found mainly on cells involved in the immune response, including antigen-presenting cells, B cells, and T helper cells, but not T killer cells. 

Sarvetnick, N., Liggitt, D., Pitts, S. L., Hansen, S. E. and Stewart, T. A. (1988). Insulin-dependent diabetes mellitus induced in transgenic mice by ectopic expression of class II MHC and interferon-gamma. Cell 52,... 

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