TRANSPLANTATION

Major Histocompatibility Complex (MHC) In Transplantation



Major Histocompatibility Complex (MHC) In Transplantation

Introduction

Definition

Major histocompatibility complex is abbreviated as MHC. A cluster of genes located on chromosome 6 concerned with antigen production and critical to the success of transplantation. The MHC includes the human leukocyte antigen (HLA) genes. (Verthelyi 2001 983-993)

Classes of MHC

There are two general classes of MHC molecules: Class I and Class II. Class I MHC molecules are found on all nucleated cells and present peptides to cytotoxic T cells. Class II MHC molecules are found on certain immune cells themselves, chiefly macrophages, B cells and dendritic cells, collectively known as professional antigen-presenting cells (APCs). (Stimson 2008 345-350) These APCs specialize in the uptake of pathogens and subsequent processing into peptide fragments within phagosomes. The Class II MHC molecules on APCs present these fragments to helper T cells, which stimulate an immune reaction from other cells.

Name

Function

Expression

MHC class I

Encodes non-identical pairs (heterodimers) of peptide-binding proteins, as well as antigen-processing molecules such as TAP and Tapasin.

All nucleated cells. MHC class I proteins contain an a chain & ß2-micro-globulin(not part of the MHC encoded by chromosome 15). They present antigen fragments to cytotoxic T-cells via the CD8 receptor on the cytotoxic T-cells and also bind inhibitory receptors on NK cells.

MHC class II

Encodes heterodimeric peptide-binding proteins and proteins that modulate antigen loading onto MHC class II proteins in the lysosomal compartment such as MHC II DM, MHC II DQ, MHC II DR, and MHC II DP.

On most immune system cells, specifically on antigen-presenting cells. MHC class II proteins contain a & ß chains and they present antigen fragments to T-helper cells by binding to the CD4 receptor on the T-helper cells.

MHC class III region

Encodes for other immune components, such as complement components (e.g., C2, C4, factor B) and some that encode cytokines (e.g., TNF-a) and also hsp.

Variable

(Sizonenko 2007 894-904)

Class III has a function very different from that of class I and class II, but, since it has a locus between the other two (on chromosome 6 in humans), they are frequently discussed together.

Transplantation

The artificial removal of part of an organism and its replacement in the body of the same or of a different individual is called transplantation. To remove a plant from one location and replant it in another place. (Miller and Valdes 2005 144-153)

Background

Stem cells have the ability to multiply and differentiate into various specialized cells under the influence of epigenetic factors. It is a one-stop source for regenerative and reparative processes of the body, since it belongs to the role of replacing the lost cells. Based on the theory of depletion of stem spaces of the body stem cells in tissues and organs is limited and determined genetically. Therefore, over the years in the body are violated, that he is unable to fix. (McFarland & Koup 2004 4215-4220)

Ability of stem cells migrate into the damaged area of tissue areas of the body, integrated into them and differentiate into various specialized cells allow their use in clinical practice, opening the prospect of ...