Sato H, Itoh T, Rikiishi H, Kumagai K
Department of Microbiology, Tohoku University School of Dentistry, Sendai, Miyagi, Japan.
Microbiol Immunol. 1994;38(2):139-47. doi: 10.1111/j.1348-0421.1994.tb01755.x.
A protein isolated from the cytoplasmic membranes of Streptococcus pyogenes (cytoplasmic membrane-associated protein, CAP) stimulated human T cells in vitro to induce their mitogenic response. This CAP-induced T cell proliferation required the presence of nylon-adherent accessory cells (AC) of either autologous or allogeneic origin in the reaction mixtures. In addition, the reaction was inhibited by monoclonal antibodies (mAbs) against major histocompatibility complex (MHC) class II molecules, HLA-DR and -DQ, but not -DP. Human lymphoid cell lines positive for HLA-DR but not those lacking it were also effective as AC for the reaction. A binding test using fluorescein-labeled protein revealed that CAP bound to the adherent monocytes and HLA-DR+ but not to -DR- lymphoid cell lines. The proliferative response of T cells to CAP was, however, not inhibited by the addition of the lysosomotrophic agent NH4Cl to the reaction mixtures. These results suggest that the presentation of CAP by AC to human T cells is mediated through binding of the protein to the MHC class II molecules but without being processed in the AC. The proliferative response of T cells was also found to be inhibited by addition of anti-CD2, -CD3 or -T cell receptor (TcR) mAbs. A major population responding to CAP was CD3+4+8- T cells. CAP also appears to stimulate T cells bearing V beta 8 sequences much more selectively than T cells bearing other V beta s. These results indicate that this streptococcal membrane protein, CAP, may be a new protein belonging to a group of bacterial superantigens.
从化脓性链球菌细胞质膜中分离出的一种蛋白质（细胞质膜相关蛋白，CAP）在体外刺激人T细胞，诱导其产生有丝分裂反应。这种CAP诱导的T细胞增殖需要反应混合物中存在自体或同种异体来源的尼龙黏附辅助细胞（AC）。此外，该反应受到针对主要组织相容性复合体（MHC）II类分子、HLA - DR和 - DQ但不包括 - DP 的单克隆抗体（mAb）的抑制。对HLA - DR呈阳性但缺乏该分子的人淋巴细胞系作为反应的AC也有效。使用荧光素标记蛋白的结合试验表明，CAP与黏附的单核细胞和HLA - DR + 结合，但不与 - DR - 淋巴细胞系结合。然而，向反应混合物中添加溶酶体营养剂NH4Cl并没有抑制T细胞对CAP的增殖反应。这些结果表明，AC将CAP呈递给人T细胞是通过该蛋白与MHC II类分子的结合介导的，但在AC中未被加工。还发现添加抗CD2、 - CD3或 - T细胞受体（TcR）mAb可抑制T细胞的增殖反应。对CAP作出反应的主要细胞群是CD3 + 4 + 8 - T细胞。与携带其他Vβ的T细胞相比，CAP似乎更有选择性地刺激携带Vβ8序列的T细胞。这些结果表明，这种链球菌膜蛋白CAP可能是属于一组细菌超抗原的新蛋白。
