[Combination of immunodepression and disorders in nucleic acid metabolism of lymphoid tissue as a manifestation of a paraneoplastic syndrome].

Several physiological, biochemical, and molecular biological approaches to the study of factors determining immunodepression in tumor-bearing animals are considered. Cancer cells release substances of nucleic and peptide nature that suppress the functional activity of macrophages and lymphocytes and stimulate cell proliferation in organs and tissues of the host. Suppressor T cells capable of inhibiting the function of helper T cells and impairing the differentiation of killer T cells are activated. The suppression of T- and B-cell-mediated immunity in the tumor host involves disturbances of nucleic acid metabolism in those cells as well as hypersecretion of glucocorticoids. The impairments of lymphocyte proliferation and differentiation that result in reduced immune responsiveness are attributable to drastic alterations in the metabolism of purine and pyrimidine nucleotides and to the damage sustained by the lymphocyte's DNA.