Allogeneic tissues

As indicated previously, the major cause of allogeneic tissue transplantation rejection is the polymorphic nature of the MHC phenotype between individuals. Polymorphism in MHC arises within the population because the genes for each of the MHC subclasses can exist in multiple different forms or alleles. For example, in humans there are at least 52 different forms of the MHC IB gene and at least 24 different forms of the MHC IA gene. It follows that individuals in a population can possess any one of the 52 different forms of MHC IB gene and any one of the 24 different forms of MHC 1A gene, so the number of different combinations for the six classes of MHC proteins is many millions. The situation is further complicated by the fact that each individual inherits and co-expresses a set of MHC I and II genes from each parent. This means that on each nucleated cell of the body there will be coexpressed paternally derived and maternally derived versions of the MHC IA, MHC IB and MHC IC molecules. The same principle will apply for coexpression upon APCs of paternal and maternal MHC II protein subclasses. 

Zhang, J. Liu, W. liu, L. 5-Carboxyfluorescein N-succinimidyl ester in detecting the degree of cross-linked allogeneic tissue. Shengwu Yixue Gongchengxue Zazhi 2010,27,816-819. 

For an allogeneic HCT, the recipient and the donor are dissimilar genetically unless they are identical twins (referred to as a syngeneic HCT). The tissue transplanted is immunologi-cally active, and thus there is potential for bidirectional graft... 

McIntosh KR et al (2009) hnmunogenicity of allogeneic adipose-derived stem cells in a rat spinal fusion model. Tissue Eng Part A 15(9) 2677-2686... 

Transplantation entails the transfer of living cells/tissue/organs from a donor to a recipient. In some cases (e.g. many skin grafting procedures) the donor and recipient are actually the same individual, and this is termed autologous transplantation. More usually, however, the donor and recipient are different individuals, and this is termed allogeneic transplantation. 

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