microbiology, Vol 140, 829-837, Copyright © 1994 by Society for General Microbiology
Phospholipids of Mycobacterium intracellulare inhibit T cell blastogenesis
H Tomioka and H Saito
Department of Microbiology and Immunology, Shimane Medical University, Japan.
A crude lipid fraction obtained from Mycobacterium intracellulare (MI whole
lipids) suppressed concanavalin A (Con A)-induced blastogenesis of murine
spleen cells (SPCs). Among three lipid fractions, the phospholipid fraction
possessed the highest inhibitory activity, followed by the polar mycoside
fraction, but the apolar mycoside fraction showed no activity. Since MI
whole lipid and phospholipid fractions inhibited the Con A-induced
proliferative response of SPCs which had been treated with Con A before the
addition of the lipid fractions, their action is not due to hindrance of
Con A binding to T cells. These two MI lipid fractions reduced
IL-2-producing ability, acquisition of IL-2 reactivity, and expression of
IL-2 receptors in Con A-stimulated T cells. However, they did not affect
IL-2-induced proliferation of an IL-2-dependent cytotoxic T cell line,
CTLL-2. When SPCs were pretreated with either MI whole lipid or
phospholipid fraction for 24 h, an irreversible reduction in Con A
responsiveness was seen only in the phospholipid-treated SPCs. The action
of these MI lipid fractions was phase-dependent and they exhibited
considerably decreased but still significant inhibitory activity against
Con A blastogenesis of SPCs, even when they were added at 24 h after the
initiation of SPC culture with Con A. MI whole lipids and the three lipid
fractions (polar mycoside, apolar mycoside, and phospholipid fractions) did
not exhibit suppressor cell-inducing activity, while MI whole lipid
fraction antagonized the Con A-mediated generation of suppressor cells.
Silica gel thin layer chromatography of the phospholipid fraction showed
four spots containing phosphate and one spot without.(ABSTRACT TRUNCATED AT
250 WORDS)
