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Macrophage‐Derived Growth Factor for Fibroblasts and Interleukin‐1 Are Distinct Entities
Author(s) -
Estes John E.,
Pledger W.J.,
Gillespie G. Yancey
Publication year - 1984
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.35.1.115
Subject(s) - biology , lymphokine , sephadex , cell culture , microbiology and biotechnology , 3t3 cells , interleukin , macrophage , lipopolysaccharide , macrophage activating factor , phytohaemagglutinin , monokine , dna synthesis , fibroblast , stimulation , biochemistry , immunology , cytokine , endocrinology , antigen , in vitro , transfection , genetics , enzyme
P388D 1 , a mouse macrophagelike cell line, was adapted to grow continuously in an unsupplemented, serum‐free culture medium and continued to elaborate substances that were mitogenic for quiescent mouse fibroblasts (BALB/c 3T3 cells) and for thymocytes suboptimally stimulated with lectins. We have previously described [37] the fibroblast mitogenic activity as a macrophage‐derived competence factor (MDCF). Serum‐free, macrophage‐conditioned culture medium was concentrated 1,000‐fold by a combination of ultrafiltration (hollow fiber) and lyophilization. Concentrates of medium were subjected to gel filtration (Sephadex G‐75 or G‐150), and the fractions were assayed for mitogenic activity (MDCF) on density‐arrested BALB/c 3T3 cells and for Interleukin‐1 (IL‐1) activity in suboptimally stimulated (Con A) mouse thymocytes. The apparent molecular weight (MW) of MDCF activity was estimated at 56,000 daltons, whereas the peak of IL‐1 chromatographed at an apparent MW of 14–16K daltons. There was no detectable IL‐1 activity in the MDCF fractions and no detectable MDCF in the IL‐1 fractions. These data indicate that P388D 1 cells produce both MDCF and IL‐1 activities under continuous serum‐free conditions and that the two activities are not identical. Stimulation of responsive mononuclear phagocytes with lipopolysaccharide and/or lymphokine‐rich supernates resulted in a differential modulation of MDCF and IL‐1 activities. Finally, antibody‐purified IL‐1 had no significant ability to stimulate DNA synthesis in quiescent fibroblasts at concentrations that were mitogenic for thymocytes. However, IL‐1 did augment the mitogenic activity of suboptimal amounts of platelet‐derived growth factor (PDGF), another competence factor. Further studies revealed that neither the generation nor the activity of MDCF was modulated by the presence of various inhibitors of proteolytic enzymes.