Chemotactic subpopulation of macrophage cell line cells (M1 cells) discerned by three macrophage chemotactic factors from delayed hypersensitivity reaction sites

Synergistic interaction of a cytokine produced by embryonic fibroblasts and a lymphokine contained in Con A-stimulated spleen cell culture for murine macrophage differentiation: a model experiment using cell line cells, M1

The modulating activity of the culture supernatant of Con A-stimulated murine spleen cells for macrophages was investigated by using M-1 cells, which could differentiate into macrophage-like cells (referred to as M+1 hereafter), cocultured in a conditioned medium (CM) containing a differentiation factor (DF) obtained from the secondary culture of murine embryonic fibroblasts. DF induced Ia antigens on M-1 cells at a high rate in parallel with the appearance of Fc-receptor (FcR)-dependent phagocytic activity for erythrocytes coated with an antibody (EA). In contrast, Con A-sup alone had no modulating effect on M-1 cells. However, the Con A-sup stimulates synergistically M-1 cells with DF. Thus, coculture of M-1 cells with Con A-sup and DF generates M++1 cells which possess higher phagocytic activity than M+1 cells. These cells also exhibited stronger accessory cell activity than M+1 cells when tested for their promoting effect on IL-2 production by Sephadex G-10-passed spleen cells. The accessory cell activity of M++1 cells was further enhanced by culture with lymphocytes in the presence of indomethacin while that of M+1 cells did not change. These findings suggest that M-1 cells probably acquire potentiating, as well as inhibitory activity at the same time when cultured with DF and Con A-sup. The functional maturation caused by Con A-sup seemed to be associated with the expression of a receptor for a lymphokine, termed phagocytosis-augmenting factor (PAF) which is present in the Con A-sup. Such a receptor appeared to be common to macrophage lineage, since PAF in Con A-sup was absorbed out with splenic adherent cells and peritoneal exudate cells (PEC) in addition to M+1 cells, but not with nonadherent splenic lymphocytes or lymphoid cell line cells, such as EL-4 and L-1210. This fact suggests that PAF is different from interferon-gamma (IFN) which is known to modulate the function of lymphocytes. Inability of PAF to bind Cibacron Blue-Sepharose, unlike IFN, supports this notion. The molecular weight of PAF is approximately 2-3 X 10(4). Thus, the present studies suggest the requirement of at least two signals for the full maturation of macrophages, a cytokine represented by DF and a lymphokine, by PAF.

Mediation of macrophage reactions in immune tissue injury

The chemotactic specificity of three types of macrophage chemotactic factors (MCF) -a, -b, and -c, from delayed hypersensitivity reaction (DHR) skin sites in guinea pigs, was analysed. MCF-c shared common antigenicity with the macrophage chemotactic lymphokine released from bovine gamma globulin (BGG) and horse radish peroxidase (HRPO) -stimulated lymphocytes, using an immunoadsorbent column conjugated with anti-MCF-c antibody. These purified lymphokines were very similar, or possibly identical in terms of physicochemical and serological properties. BCG-induced lymphokine seemed to exist as complexes with serum protein at the skin site. A change in the proportion of each MCF was observed during the development of DHR. Furthermore, MCF-a and -b attracted Ia- M1 cell line cells, while MCF-c attracted Ia+ cells. Moreover, the responsive guinea-pig monocytes were divided mainly into two distinctive migrating subpopulations. One subpopulation was responsive to MCF-a and -b, and the majority of responding cells were "Ia-negative". The second subpopulation was responsive to MCF-c and the predominant cell type was "Ia-positive". The data suggest that macrophage reactions in the DHR are mediated by MCF-a, -b, and -c and that MCF-c attracts Ia bearing accessory macrophages and MCF-a and b- attract Ia negative macrophages.

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.