Y. Esaki et al., ROLE OF HUMAN MAJOR HISTOCOMPATIBILITY COMPLEX DQ MOLECULES IN SUPERANTIGENICITY OF STREPTOCOCCUS-DERIVED PROTEIN, Infection and immunity, 62(4), 1994, pp. 1228-1235
Antigenicity of peptic extract from type 12 group A streptococci (PEAS
T12) for T cells was examined in major histocompatibility complex (MHC
) class II transgenic mice. PEAST12 was mitogenic for murine T cells w
hen antigen-presenting cells were obtained from human MHC (HLA)-DQ4 al
pha beta transgenic mice or from DQ6 alpha beta transgenic mice but wa
s not mitogenic in DR alpha transgenic, DR51 alpha beta transgenic, Ec
u transgenic, or nontransgenic mice. In addition, PEAST12 showed mitog
enicity for murine T cells in DQ4 alpha singly transgenic mice but not
in DQ4 beta singly transgenic mice. T-cell stimulation by PEAST12 was
unrestricted by but dependent on the expression of HLA-DQ molecules o
n antigen-presenting cells, and PEAST12 selectively activated T-cell r
eceptor V beta 11-, V beta 15-, and V beta 18-positive T cells in mice
. We propose that PEAST12 contains a superantigen which binds preferen
tially to the alpha-chain of HLA-DQ molecules. The well-known phenomen
on that peptic extracts from group A streptococci are mitogenic in hum
ans but not in mice is likely due to structural differences in MHC cla
ss II molecules between these two species of mammals.