Antigenicity of peptic extract from type 12 group A streptococci (PEAST12) for T cells was examined in major histocompatibility complex (MHC) class II transgenic mice. PEAST12 was mitogenic for murine T cells when antigen- presenting cells were obtained from human MHC (HLA)-DQ4αβ transgenic mice or from DQ6αβ transgenic mice but was not mitogenic in DRα transgenic, DR51αβ transgenic, Eα transgenic, or nontransgenic mice. In addition, PEAST12 showed mitogenicity for murine T cells in DQ4α singly transgenic mice but not in DQ4β singly transgenic mice. T-cell stimulation by PEAST12 was unrestricted by but dependent on the expression of HLA-DQ molecules on antigen-presenting cells, and PEAST12 selectively activated T-cell receptor Vβ11-, Vβ15-, and Vβ18-positive T cells in mice. We propose that PEAST12 contains a superantigen which binds preferentially to the α-chain of HLA-DQ molecules. The well-known phenomenon that peptic extracts from group A streptococci are mitogenic in humans but not in mice is likely due to structural differences in MHC class II molecules between these two species of mammals.
|Number of pages
|Infection and Immunity
|Published - 1994
All Science Journal Classification (ASJC) codes
- Infectious Diseases