Effect of BCG (Tice strain) on primary sensitization to 2,4-dinitrochlorobenzene and on established delayed hypersensitivity in human malignant melanoma.

Studies of primary sensitization and delayed hypersensitivity reactions to 2,4-dintrochlorobenzene (DNCB) and recall antigens were conducted in 71 patients with melanoma who were receiving BCG (Tice strain) immunotherapy by scarification. Similar studies were conducted in 32 control patients with melanoma who did not receive BCG. No significant differences were observed, in the various clinical stages, between patients receiving and those not receiving BCG, in terms of the frequency or intensity of primary sensitization to DNCB. Furthermore, there was no significant difference in delayed hypersensitivity to recall antigens between these groups of patients. The apparent discrepancy between the clinical benefit from BCG immunotherapy and its failure to stimulate certain parameters of cellular immunity in patients with melanoma is discussed.