title: Cell interactions at the level of mature antibody producers: the properties of the bone marrow humoral factor stimulating antibody production.
abstract: The soluble factor recovered from supernatants of cultures of normal mouse bone marrow cells and previously isolated on Sephadex G-50 (n. w. 13,000 daltons), which stimulates antibody production when given at the peak of immune response, was further characterized in the present study. This stimulant of antibody producers (SAP) is active both in vitro and in vivo on PFC responses, and its effect does not show allogeneic or xenogeneic restriction. Using protein, RNA and DNA synthesis inhibitors, it was found that, in order to abolish the enhancing activity of treated bone marrow cells, protein synthesis must be inhibited by more than 80% and RNA synthesis by 20%, whereas inhibition of DNA synthesis by almost 100% did not interfere with the enhancing activity of treated cells. The stimulating activity of SAP was abolished by both RNase and pronase treatments, but heating at 100 degrees C for 10 min did not affect this activity. These properties indicate that SAP is a ribonucleoprotein complex. It is suggested that SAP mediates the regulatory function of bone marrow cells at the level of mature, differentiated cells of the B series.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000921:Antibody-Producing Cells / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology*; D002417:Cattle; D002450:Cell Communication; D004247:DNA / Q000096:biosynthesis; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006358:Hot Temperature; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D011402:Pronase / Q000494:pharmacology; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D012260:Ribonucleases / Q000494:pharmacology; D012756:Sheep; D013552:Swine
chemical_list: D012313:RNA; D004247:DNA; D012260:Ribonucleases; D011402:Pronase