MHC processing

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. 

Potter NS, Harding CV Neutrophils process exogenous bacteria via an alternate class 1 MHC processing pathway for presentation of peptides to T lymphocytes. J Immunol 2001 167 2538-2546. 

Figure 7. FL deliver OVA into the class 1 MHC processing pathway.

The class II cytokine receptor family includes receptors for interferon a/P (lEN a/P) and y (lENy) and IL-10. lEN-y immunoreactivity has been found in neurons in the hypothalamus, cerebral cortex, mammilary nuclei, and dorsal tegmentum. Astrocytes and microglia in vitro can be stimulated to express class II histocompatibiHty complex (MHC-II) antigens by lEN-y, which may be involved in the presentation of antigen to T-ceUs by astrocytes. Thus lEN-y may be critical in CNS-immune function and dysfunction especially in regard to neuronal and gHal apoptotic processes. 

Antigen-presenting cells (APCs) are cells of the immune system that are able to process and present foreign antigens to effector cells. The antigen is presented in the context of an MHC-I or MHC-II molecule on APCs in the presence of so-called costimulatory molecules to activate the effector cells. 

IFN- 3 reduces the induction by inflammatory cytokines of adhesion molecules and of MHC class I and II complex on endothelial cells, a process preceding attachment and transendothelial migration of T-cells. These anti-inflammatory effects of IFN- 3 exemplify antagonistic actions of type I and type IIIFN. There is, indeed, much clinical evidence for the involvement of IFN-y in inflammatory processes - through activation of iNOS and subsequent secretion of NO - leading to the establishment of autoimmune diseases as for instance in rheumatoid arthritis. 

Campbell R.D. Trowsdale J. (1993) Map ofthe human MHC. Immunol Today, 14, 349-352. Germain R.H. Marguiles D.M. (1993) The biochemistry and cell biology of antigen processing and presentation. Ann Rev11, 403-450. 

MHC [Mitsubishi hydrocracking] A process for making benzene and other aromatic hydrocarbons by hydrogenating cracked petroleum fractions. 

MHC Unibon [Mild hydrocracking] A mild hydrocracking process for desulfurizing gas oil and converting it to lower molecular weight hydrocarbons, suitable for further processing by catalytic cracking. Developed by UOP. 

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