Serum-Mediated Inhibition of Lymphocyte Stimulation by Autochthonous Human Tumors 2

Specimens from biopsies of human sarcomas and other tumors treated with mitomycin C stimulated autochthonous lymphocytes to increased DNA synthesis in the mixed lymphocyte target-interaction test. Autochthonous sera from patients with tumors inhibited the stimulatory effect. A collection of allogeneic sera was tested against one fibrosarcoma-lymphocyte combination that gave a regularly positive stimulatory interaction. The sera of patients with sarcomas blocked the lymphocyte-stimulating interaction significantly, but not of patients with other tumors, and of most healthy controls. The blocking effect of serum from a patient with fibrosarcoma diminished temporarily after the tumor was excised.