IMMUNO-SUPPRESSIVE EFFECT OF HUMAN MACROPHAGES .1. EVIDENCE FOR AN UNSTABLE SOLUBLE FACTOR(S) INHIBITING DNA-SYNTHESIS AND PROLIFERATION IN PHA-STIMULATED LYMPHOCYTES

  • 1 January 1978
    • journal article
    • research article
    • Vol. 86  (4) , 179-186
Abstract
Macrophages obtained by culturing blood monocytes in vitro for 8 days showed capacity to inhibit DNA synthesis and cell proliferation in PHA[phytohemagglutinin]-stimulated lymphocytes separated from the macrophages by a membrane with pore size 0.2 .mu.m. DNA synthesis was measured as 3H thymidine incorporation and proliferation as cell counts. The depression was reduced when the distance between macrophages and lymphocytes was increased concomitant with increased culture volume. Heat-killing of macrophages abolished their lymphocyte depressing capacity. Full inhibitory effect was established within 4 h when lymphocytes were cultured in the proximity of macrophages. The effect was blocked by molecular filtration membranes with nominal MW limits (nmwl) 1000 and 10,000 whereas membranes with nmwl 25,000 only partially blocked the effect. No inhibitory effect was registered in the supernatants from macrophage-depressed lymphocyte cultures. Presumably the lymphocyte depressing effect is mediated via an unstable soluble factor(s).