Abstract
Cancer-free individuals from family agregates of seemingly hereditary colon carcinoma were studied to determine the nature of their cell-mediated immune capacities in miexed leukocyte culture. Members of families who demonstrated no evidence of a precancerous condition such as polyposis coli did demonstrate substantial cellular immunopathology. Of these, 44% showed a decreased responsiveness of their peripheral mononuclear cells to allogeneic stimuli, and in a number of these individuals this deficiency clearly manifested itself as an inappropriate suppression of potentially normal lymphocyte blastogenic capacities by an adherent population of mononuclear leukocytes. This in vitro defect of recognitive immunity appears to be the same type of defect that has already been described for individuals with established maligancies. The pattern of phenotypic expression of this immunopathology within these families is not inconsistent with an hereditary disorder. Individuals from families with a known hereditary somatic precancerous condition usually did not demonstrate this immunopathology. It is appropriate to speculate that the defect of recognitive immunity in the former families could be contributory to the genesis of the colon carcinoma.