Mechanisms of HLA DR Gene Selection in Early Ontogenesis.

Hypothesis explaining the cause of MHC gene frequency variation in two consecutive generations is presented. The four stages of MHC genes selection is postulated: gamete processing, reaction of fertilization, preimplatation and implatation embryos survival, postnatal selection. On the stage of gametogenesys different adaptivity of germ cells is connected with MHC alleles. On the stage of fertilization and implantation the main factor of selection is cell-to-cell polar interaction with the participation of MHC: spermatozoa and ovum; cleavaging cells of early embryo; cells of early embryo and endometrium. On the stage of development of implantation embryo the essential role play MHC-restricted immune mother-fetus interactions. Postnatal selection is connected with more or less resistance of children and adults to MHC-associated diseases.