Studies on antilymphocyte antibodies in gestational choriocarcinoma

The mixed lymphocyte reaction (MLR)-blocking activity of sera was examined in patients with gestational choriocarcinoma. The frequencies of human leukocyte antigens (HLAs) in seven choriocarcinoma patients and their husbands were not different from those in the normal Japanese population. In patients who were successfully treated, many mismatches were found between the woman's HLA-A, B, C antigens and those of her spouse. Sera from three patients showed cytotoxic activity against their husbands' T lymphocytes. Similar results were obtained with sera absorbed with platelets to test for cytotoxic activity against the husbands' B lymphocytes. Cytotoxic activity sometimes disappeared at the recovery stage of the disease. Significant MLR-blocking activity was found in sera of patients in a tumor-bearing stage, but was absent 3-4 months after serum human chorionic gonadotrophin levels dropped into the normal range. It reappeared when patients relapsed, showing that MLR-blocking activity reflected tumor burden. The MLR-blocking factors in patients' sera may not be identical to the so-called serum nonspecific immune inhibitor factors, but was specific to, or dependent on, the use of the husbands' lymphocytes as stimulator cells and was mediated by immunoglobulin (antibodies) reactive with antigens expressed on the husbands' B lymphocytes, e.g. the MHC class II antigens.