Tumor-directed immunity in neuroblastoma patients and their related and unrelated contacts.

Tumor-directed cell-mediated and humoral immunity were assessed in vitro in neuroblastoma (NB) patients, and also in their relatives and genetically unrelated contacts, using the one-stage, direct, capillary leukocyte migration inhibition (LMI) test and the indirect, membrane, immunofluorescence test (IFT), respectively. Leukocytes from 83% and sera from 50% of NB patients examined were selectively reactive with NB cells, and materials derived from them. Genetically unrelated contacts as well as relatives of NB patients showed NB-directed immunity, the frequency of which increased with increasing closeness of contact with these patients. These findings suggest that the environment of NB patients may contain some tumor-derived material which induces detectable sensitization in those sharing that environment. Such tumor-derived material would appear to have a high degree of infectivity, low degree of oncogenicity, and probably also a low general pathogenicity.