[Immunosuppressive macrophages induced in Mycobacterium avium complex infection induced in mice].
Profiles of generation and characteristic of splenic macrophages (M phi s), which suppress the ConA mitogenic response of splenic T cells, induced in mice during the course of Mycobacterium avium complex infections were investigated. In MAC-infected mice, reduction of ConA mitogenesis of spleen cells (SPCs) was seen after week 2 and the reduced state thereafter durated as long as at least for 8 weeks. Splenic M phi s with a potent suppressive activity against SPC mitogenesis were transiently induced around 2 weeks after infection. Splenic M phi s of BALB/c (MAC-susceptible) mice had similar but somewhat weaker suppressor activity, as compared to those of CBA/JN (MAC-resistant) mice. The suppressor activity of BALB/c M phi s durated much longer than did CBA/JN M phi s. MAC-induced splenic M phi s were markedly elevated in chemiluminescence and this coincided with increase in immunosuppressive activity. These M phi s inhibited the generation of IL-2-reactive T cell populations in response to ConA-signals, without showing any inhibitory effect against IL-2 producing ability of target T cells. Because immunosuppressive M phi s having the same characteristics were also induced in BALB/c athymic nude mice, thereby indicating that mature T cells are not prerequisite for induction of the present suppressor M phi s in MAC-infected host mice. Prostaglandins (PGs), nitric oxide radical (NO.) and free long chain fatty acids are thought to play certain role in the expression of suppressor action of MAC-induced M phi s, because of the following reasons.(ABSTRACT TRUNCATED AT 250 WORDS)
Tomioka
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H
Department of Microbiology and Immunology, Shimane Medical University, Izumo, Japan.
Saito
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H
D000818:Animals; D007108:Immune Tolerance; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D008819:Mice, Nude; D009162:Mycobacterium avium; D013601:T-Lymphocytes / Q000276:immunology; D014376:Tuberculosis / Q000276:immunology*