IMMUNOSUPPRESSIVE 30-KDA PROTEIN IN URINE OF PREGNANT-WOMEN AND PATIENTS WITH TROPHOBLASTIC DISEASES

Urine samples obtained from normal pregnant women and patients with tr ophoblastic diseases contain 30-kDa protein that suppresses phytohemag glutinin-induced T cell proliferation. The immunosuppressive protein w as measured by a newly developed radioimmunoassay. The 30-kDa protein was demonstrated in almost all urine samples examined, fluid from hyda tid vesicles and chorionic extracts, but not in any serum samples exce pt at low levels in some sera from patients with choriocarcinoma. Duri ng pregnancy, the level of urinary 30-kDa protein was higher in the fi rst (1625.5 +/- 1212.0 ng/ml, mean +/- S.D.) and second (1457.4 +/- 13 32.4 ng/ml) trimesters than in the third trimester (460.6 +/- 419.0 ng /ml). The urinary 30-kDa protein/hCG ratios in patients with choriocar cinoma (8.3 +/- 10.9) were significantly higher than those in patients with hydatidiform mole (0.67 +/- 1.00, P < 0.01) and in all trimester s than those of normal pregnant women (0.54 +/- 0.44 in the first trim ester, P < 0.05; 0.63 +/- 0.46 in the second trimester, P < 0.05; 0.24 +/- 0.17 in the third trimester, P < 0.01). There is no significant d ifference between the ratios in hydatidiform mole and normal pregnancy . These findings and the fast disappearance of the 30-kDa protein from the circulation suggest that the 30-kDa protein plays a part in proli feration of trophoblastic cells in, or their invasion into the host by locally suppressing the immune reaction of the host and that the incr ease in the urinary 30-kDa protein level, in cases of choriocarcinoma, may be due to the malignant transformation of trophoblastic cells res ulting in their rapid invasion.