Reaction of the leukocytes of melanoma patients and control donors, including pregnant women, with melanoma- and fetus-derived materials.

Using a one-stage capillary leukocyte migration inhibition assay, we examined peripheral blood leukocytes from 97 patients with malignant melanoma, 194 pregnant women, and 123 non-pregnant donors for their reactivity with materials from fetal and melanomatous tissues. As in previous studies, we found melanoma extracts selectively to inhibit melanoma patients' leukocytes. First-trimester fetal extracts also selectively inhibited melanoma patients' leukocytes, suggesting their cross-reactivity with melanoma-derived antigens. We could not localize the source of the inhibitory materials within the fetuses. We found no evidence that pregnant women were selectively immunized to fetal or melanoma extracts, regardless of their parity or the stage of their pregnancy.