Cellular events accompanying regression of skin recurrences of breast carcinomas treated with intralesional injections of natural interferons alpha and gamma.

Cutaneous recurrences of breast carcinomas were treated with 10 i.l. injections of nIFNs alpha and gamma delivered in combination (7 lesions) or singly (11 with nIFN-alpha, one with nIFN-gamma). Histologically confirmed complete regressions occurred in 5 of 7 lesions treated with nIFN-alpha/nIFN-gamma and in 5 of 11 recurrences injected with nIFN-alpha alone. In all cases specimens were obtained before and after therapy. In addition, in some cases (4 treated with nIFN-alpha/nIFN-gamma, 2 with nIFN-alpha, one with nIFN-gamma) multiple recurrences were injected simultaneously and were excised 24 h after 1, 3, and 10 injections and 21 days after completion of therapy. The main findings observed in the treated lesions undergoing complete and partial regressions included: (a) inhibition of mitotic activity and up-regulation of antigenic expression (mammary epithelial membrane antigen, intercellular adhesion molecule 1, HLA-DR) by the carcinoma cells; (b) activation of macrophages and dendrocytes with marked expression of HLA-DR and HLA-A,B,C; (c) infiltration of the dermis and tumors by activated T-lymphocytes (CD3+, CD4+, CD8+); (d) questionable participation by B-lymphocytes and natural killer cells; (e) activation of endothelium with enhancement of antigenic expression (intercellular adhesion molecule 1, HLA-DR), procoagulant activity, and vascular permeability. The responses elicited by nIFN-alpha/nIFN-gamma were greater than those caused by either IFN used alone. It appears that in these patients the IFNs exerted an antiproliferative action and potentiated a cell-mediated immunological response liminally present in the neoplastic tissues prior to therapy.