Antigen-enhanced glucosamine incorporation by peritoneal macrophages in cell-mediated hypersensitivity. I. Studies on biology and mechanism.

The interaction between sensitized lymphocytes and specific antigen occurring in classic delayed hypersensitivity causes guinea pig peritoneal macrophages to incorporate increased amounts of glucosamine into TCA precipitable, membrane-associated, cell surface material. Antigen-induced stimulation of glucosamine also occurred in peritoneal exudate cells (PEC) isolated from animals primed for cutaneous basophil hypersensitivity with certain strong antigens (KLH, vaccinia virus) in incomplete Freund's adjuvant (IFA), and lymphocytes from such animals elaborated MIF when cultured with specific antigen. Thus, the use of complete Freund's adjuvant is not obligatory for the induction of sensitized lymphocytes capable of secreting MIF or stimulating macrophage glucosamine incorporation; however, the potency of the immunogen employed is a critical variable since lymphocytes from animals primed with weaker antigens (HSA, BGG) in IFA did not have these capabilities. Significantly enhanced incorporation of radioactive glucosamine by macrophages occurred when normal PEC were cultured in lymphokine-containing supernatants, but the magnitude of incorporation was smaller than that of sensitized PEC stimulated by antigen. The final 24 hr of macrophage culture was critically important because lymphokines were equally effective in promoting glucosamine incorporation when present for only this interval. The kinetics of this response are thus very similar to those reported for macrophage "activation". The mechanism by which sensitized lymphocytes and their products stimulate glucosamine incorporation is not established, but at least part of the increment may be attributed to enhanced transport of glucosamine across the macrophage plasma membrane. The plant lectins Con A and PHA stimulated unsensitized plastic-adherent cells to increased glucosamine in corporation and exerted a further additive stimulation on sensitized PEC when nonadherent sensitized lymphocytes were present. It is likely that these mitogens stimulate glucosamine incorporation by two distinct mechanisms, one involving sensitized nonadherent lymphocytes and a second involving only adherent cells (macrophages and/or plastic adherent lymphocytes.

Chemotaxis of basophils by lymphocyte-dependent and lymphocyte-independent mechanisms.

Guine pigs basophils obtained from blood or bone marrow have been studied for their chemotactic responsiveness. Chemotactic factors for basophils include a substance (lymphokine) present in culture fluids from antigen-stimulated lymphocytes, a material generated in zymosan-activated guinea pig serum, a C5 cleavage factor, and a bacterial factor. When compared with homologous neutrophils and monocytes, basophils respond most rapidly to a chemotactic stimulus. The lymphokine basophil chemotactic factor is physicochemically similar to the previously described monocyte chemotactic factor but appears to be distinct from it as well as MIF and neutrophil chemotactic factor present in the same fluids, Part of the evidence for this is the ability to detect basophil chemotactic factor in the absence of other lymphokine activities under appropriate experimental conditions. More evidence, specifically relating to the monocyte factor, is that monocytes can adsorb basophil chemotactic activity but not vice versa. This latter observation may have implications for the mechanism whereby the accumulation of basophils is controlled and limited in vivo. In addition, it was noted that specific antigen could also suppress basophil chemotaxis. Although the mechanism of this phenomenon is unclear, it could serve as a second means by which basophil accumulation may be controlled in the intact animal. Taken together, these observations provide further definition of the chemotactic behavior of basophils in general, and underscore some of the ways in which lymphocytes can influence basophils through lymphokine-dependent mechanisms.

MIF-like activity in simian virus 40-transformed 3T3 fibroblast cultures.

Simian virus 40-transformed fibroblasts (SV3T3), as compared with their untransformed counterparts (3T3), elaborate a macromolecular product that inhibits macrophage migration and causes macrophages to aggregate and lose one type of cell coat material. I'he SV3T3 cells also lack this surface material relative to 3T3 cells. There may be a relationz between migration inhibition factor (MIF), the cell coat, and cell migration.