Discussion paper: effect of supernatants from long-term lymphoid cell lines on metastatic cutaneous tumors following local injection.

A fraction with lymphokine properties was isolated from supernatant medium of the continuous cultured human lymphoblast cell line, 1788. Culture medium containing 2% human serum was used for cell growth in order to minimize antigenicity of supernatant fractions isolated from the medium. The culture medium was passed through an Amicon XM-100 membrane, concentrated over a PM-10 membrane, lyophilized, and reconstituted to a final concentration of approximately 40:1. Studies in vivo and in vitro showed that the active fraction contained skin reactive factor (when injected intradermally into guinea pigs and humans), lymphotoxin, migration inhibition factor, chemotactic factor, and macrophage activation factor. This same preparation, when injected intralesionally into cutaneous tumors, induced an inflammatory reaction followed by tumor regression. The fraction confined between membranes of pore size 10,000-100,000 daltons was active in promoting tumor regression, while the fraction less than 10,000 daltons was inactive. Patients with skin lesions from metastatic carcinoma of the breast and other malignancies were studied, and 16 out of 30 treated lesions were judged to have undergone either complete or greater than 50% regression. Of these, 8 were biopsied before and after lymphokine injection, and 6 out of 9 were negative for tumor cells. Additional studies in vitro with material fractionated on Sephadex G-200 indicated that the macrophage-activating component binds to alpha-2 macroglobulin in the culture medium.