Capping of mouse spleen lymphocyte C3 receptors: effects of pharmacologic agents
Gormus, B.J.; Basara, M.L.; Arneson, M.A.; Kaplan, M.E.
Journal of Immunology 124(6): 2747-2753
1980
ISSN/ISBN: 0022-1767 PMID: 7373047 Document Number: 157027
Bacteria [Salmonella typhimurium] (B)-antibody(A)-complement(C) complexes (BAC) were used to study the mechanism of C3 receptor (C3R) capping after rosette formation with mouse spleen lymphocytes (MSL). At 0.5.degree. C no capping of C3R rossettes occurred, whereas, at 37.degree. C, C3R capping occurred rapidly (.ltoreq. 15 min) and the rate was enhanced by colchicine (CLC), but not by lumiCLC. Incubation of BAC-rosetted MSL at 37.degree. C resulted in the stimulation of motility coincidentally with capping of C3R in cells that bound BAC. The number of motile BAC-rosetted and nonrosetted cells was increased by CLC, whereas cytochalasin B(CB) totally abolished motility and C3R capping. Cytochalasin A(CA) also abolished C3R capping. C3R capping was markedly diminished by agents that inhibit glycolysis (2-deoxy-D-glucose, fluoride and iodoacetamide) or that interfere with energy production (azide, cyanide and dinitrophenol). Cyclohexemide, a potent inhibitor of protein synthesis, had no effect on capping over a wide range of concentrations. These observations indicate that binding of BAC to lymphocyte C3R stimulates cell motility and that capping of MSL C3R is enhanced by CLC, a drug that stimulates cell motility and prevents polymerization of tubulin into microtubules (MT); inhibited by cytochalasins A and B, which disrupt microfilaments (MF) and inhibit cell motility; inhibited by agents that interfere with cellular energy metabolism; and independent of protein synthesis. These properties suggest that C3R capping is an active process that is associated with the cytoskeletal-contractile system. Capping of MSL C3R and cell motility are apparently interrelated, but probably separable, events. C3R and surface immunoglobulin (SIg) did not cocap, i.e., capping of R did not affect the distribution of the other. Cells that were labeled with anti-Ig and BAC in ice, and then incubated at 37.degree. C, capped both SIg-anti-Ig and BAC-C3R at identical poles on 80% of cells labeled with both ligands. These observations, together with other similarities in capping properties of SIg and C3R, suggest that SIg and C3R cap by similar mechanisms.