Immunology of Early and Late Ontogenesis

Immunological interrelations are one of the most important factors, forming all the periods of ontogenetic body development. At early ontogenesis in the organism of mammals, including humans, the immunological tolerance is induced to own (self) antigens that prevents the development of autoimmune reactions in adult life. The system of immune recognition reaches its fine discriminative capacity in mammals and humans on the background of recognition of self HLA class I (CTL of CD8(+) phenotype) or class II (T helpers of CD4(+) phenotype). The phenomenon of major histocompatibility complex (MHC) restriction reactivity of cytotoxic T lymphocytes (CTL) makes difficult the recognition in changes or mutations in HLA system. Natural killers (NK) control constantly the structure of self MHC class I molecules, and in contrast to CTL may recognize small antigenic changes of MHC molecules, induced by viruses, mutations and transformation. Immune system aging is displayed by both quantitative, and functional changes in lymphocyte subpopulations with prevalence of T helpers type 2 over type 1 cells, responsible for the development of DTH. According to immunological theory of aging, the role of immune system cells should be taken into consideration in relation to the synthesis of activated oxygen forms with bactericidal properties by monocytes and neutrophils. Overproduction of activated oxygen radicals may result in destruction of proteins, lipids, DNA, and in the body aging. Activated oxygen radicals are one of events of lymphocyte apoptosis in aerobic conditions.