Characterization of antibodies reacting with husband's lymphocytes in sera from patients with trophoblastic malignancies.

Lymphocytotoxic antibodies reacting with husband's lymphocytes were demonstrated in 24 sera from women with trophoblastic neoplasia studied before any chemotherapy. These antibodies exhibited a maximal cytotoxic activity at +4 degrees C. They reacted mainly with B lymphocytes as assessed by microlymphocytotoxicity assays using B- or T-cell enriched subpopulations and T- or B-cell lines as targets. They could not be absorbed out with platelets or erythrocytes, and did not react with autologous lymphocytes. In one double-labelling immunofluorescence experiment, these antibodies could be stained by rhodamine-conjugated Fab'2 anti-mu fragments and thus appeared to belong to the IgM class. They were shown to react mainly with surface Ig (SIg) bearing lymphocytes, plus a minor SIg negative subset. Studies with panels of allogeneic normal B cells and of HLA homozygous B-cell lines showed that the target antigen(s) recognized by these antibodies is clearly distinct from HLA-D antigens. Corresponding antigens seem to be expressed on placenta, since the lymphocytotoxic antibodies could be absorbed out with trophoblastic homogenates and one serum reacted with JAR cells (cultured choriocarcinoma line). An enhancing role of such antibodies in the growth of trophoblastic malignancies may be suggested.