SUPPRESSOR CELL ACTIVITY IN TUMOR-BEARING MICE .1. DUALISTIC INHIBITION BY SUPPRESSOR T-LYMPHOCYTES AND MACROPHAGES

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 120  (4) , 1345-1353
Abstract
Spleen cells from mice bearing methylcholanthrene-induced fibrosarcomas impaired mitogen responses of normal syngeneic lymphocytes. Nylon wool column and other depletion techniques were utilized to characterize the cellular source of suppressive activity in tumor-bearing host (TBH) spleens. Evidence is presented for 2 distinct suppressor cell systems operating in the spleens, but not lymph nodes, of BALB/c mice bearing transplanted tumors. Spleens from TBH had greatly increased numbers of macrophages over their normal counterparts. TBH macrophages had suppressive activity at low in vitro concentrations. Anti-Thy 1 serum treatment of TBH macrophages abrogated low dose inhibition but not suppression due to high numbers of macrophages. No functional difference was detected between anti-Thy 1 serum-treated TBH and normal splenic macrophages. In a macrophage-depleted culture system, mildly nylon wool adherent, anti-Thy 1 serum and hydrocortisone succinate-sensitive suppressor cells could be detected. Soluble supernatant products of TBH spleen and thymus cells inhibited in vitro mitogen responses. TBH macrophages and lymph node cells demonstrated no soluble suppressive activity. The major source of soluble inhibitor of DNA synthesis seems to be an anti-Thy 1 serum, hydrocortisone-sensitive population.