Antigen provoking gamma interferon production in response to Mycobacterium bovis BCG and functional difference in T-cell responses to this antigen between viable and killed BCG-immunized mice.
It has been shown that gamma interferon (IFN-gamma)-producing CD4+ T cells, which are generated only by immunization with viable bacteria, exert a significant role in protective immunity against mycobacteria in mice. In this study, we have tried to determine the antigen recognized by the T cells in search of a possible protective antigen. T cells from viable Mycobacterium bovis BCG-immunized mice were stimulated with several antigens, and IFN-gamma production was measured. Purified protein derivative and viable and killed BCG lysates caused significant IFN-gamma production, and almost the same level of IFN-gamma activity was detected in both groups stimulated with viable and killed BCG lysates. However, heat shock protein (HSP) 65 and HSP 70 were not a major antigen for IFN-gamma production. The antigen provoking IFN-gamma production is localized mainly in the membrane fraction of BCG cells, and the approximate molecular size was 18 kDa. On the other hand, T cells from killed BCG-immunized mice never responded to this antigen for IFN-gamma production, whereas they could mount a delayed-type hypersensitivity response. These results showed that the antigen provoking IFN-gamma production was present in killed as well as viable BCG. In addition to the antigen presentation by antigen-presenting cells, some kinds of differentiation factor (such as monokines) that are produced only by stimulation with viable cells seemed to be necessary for the development of IFN-gamma-producing T cells.
Kawamura
I
I
Department of Bacteriology, Niigata University School of Medicine, Japan.
Yang
J
J
Takaesu
Y
Y
Fujita
M
M
Nomoto
K
K
Mitsuyama
M
M
D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis / Q000276:immunology*; D001500:BCG Vaccine / Q000276:immunology*; D002478:Cells, Cultured; D006968:Hypersensitivity, Delayed; D007114:Immunization; D007371:Interferon-gamma / Q000096:biosynthesis*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D013601:T-Lymphocytes / Q000276:immunology*; D015164:Vaccines, Inactivated / Q000276:immunology
D000942:Antigens, Bacterial; D001500:BCG Vaccine; D015164:Vaccines, Inactivated; D007371:Interferon-gamma