Immunological basis of close-contact sensitization to osteosarcoma

Normal persons with a history of close contact with cancer patients often given positive responses in tests for specific tumor immunity. The present study was designed to establish the immunological relevance of such reactivity. Leukocyte adherence inhibition analysis was used to test responses of osteosarcoma (OS)-positive donors to extracts of OS. The test system proved highly specific in that positive leukocyte adherence inhibition responses were detected in 35 of 39 OS patients while only 6 to 7% of the controls were positive. Thus, the test system appears useful in the detection of OS. Two persons reactive presumably because of exposure to OS tissue gave booster-like leukocyte adherence inhibition responses on each reexposure. Reactivity was abrogated by treatment of their leukocytes with a goat anti-T-cell immunoglobulin G. Thus, the reactivity of cells from normal donors exposed to OS probably has an immunological basis, since the test system was highly specific, reflected anamnestic reactivity, and depended on lymphocytes (probably thymus dependent). These findings suggest that an OS-associated antigen can be transmitted horizontally, but the relation of immunity to risk remains obscure.