Differential suppression activity induced by paternal leukocyte immunization in habitual abortion.

In order to investigate the possible role of suppressor cells in paternal leukocyte immunization to prevent recurrent miscarriages, peripheral blood lymphocytes from habitually aborting women before and after immunization were assessed. Immunization-induced suppressor activity as shown by (1) rise in CD8-positive cells and a decline in the CD4/CD8 ratio, (2) failure of cyclosporine A to inhibit the proliferation of phytohemagglutinin- and alloantigen-stimulated cells and (3) unresponsiveness to the immunizing spouses' antigen. These findings resembled those in normal pregnant women. Hence, paternal leukocyte immunization may induce specific and nonspecific T cell suppression which may induce the immune tolerance necessary to maintain pregnancy.