title: Profiles of cell-to-cell interaction of Mycobacterium intracellulare-induced immunosuppressive macrophages with target T cells in terms of suppressor signal transmission.
abstract: Previously, we have found that immunosuppressive macrophages (M(phi)s) induced by Mycobacterium intracellulare-infection (MI-M(phi)s) required cell contact with target T cells to express their suppressor activity against concanavalin A (Con A)-induced T cell mitogenesis. In this study, we examined the profiles of cell-to-cell interaction of MI-M(phi)s with target T cells. First, MI-M(phi)s displayed suppressor activity in an H-2 allele-unrestricted manner, indicating that MHC molecules are not required for cell contact. The suppressor activity of MI-M(phi)s was reduced markedly by paraformaldehyde fixation or treatment with cytochalasin B or colchicine, indicating that vital membrane functions are required for their suppressor activity. Secondly, the suppressor activity of MI-M(phi)s was independent of cell-to-cell interaction via CD40 ligand/CD40 and M(phi)-derived indoleamine 2,3-dioxygenase, which causes rapid degradation of tryptophan in T cells. Thirdly, precultivation of splenocytes with MI-M(phi)s, allowing cell-to-cell contact, reduced Con A- or anti-CD3 antibody-induced mitogenesis but not phorbol myristate acetate/calcium ionophore A23187-elicited proliferation of T cells. In addition, co-cultivation of T cells with MI-M(phi)s caused marked changes in profiles of the tyrosine phosphorylation of 33 kDa, 34 kDa and 35-kDa proteins and, moreover, the activation of protein kinase C and its translocation to the cell membrane. It thus appears that suppressor signals of MI-M(phi)s, which are transmitted to the target T cells via cell contact, principally cross-talk with the early signalling events before the activation of PKC and/or intracellular calcium mobilization.
authors.affiliation: Department of Microbiology and Immunology, Shimane Medical University, Izumo, Shimane, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ogasawara
authors.forename: H
authors.initials: H
authors.lastname: Tomioka
authors.forename: T
authors.initials: T
authors.lastname: Shimizu
authors.forename: C
authors.initials: C
authors.lastname: Sano
authors.forename: H
authors.initials: H
authors.lastname: Kawauchi
authors.forename: K
authors.initials: K
authors.lastname: Sato
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000276:immunology; D007108:Immune Tolerance; D066298:In Vitro Techniques; D008264:Macrophages / Q000201:enzymology / Q000276:immunology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015269:Mycobacterium avium Complex / Q000276:immunology* / Q000472:pathogenicity*; D015270:Mycobacterium avium-intracellulare Infection / Q000276:immunology*; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology
chemical_list: D011493:Protein Kinase C