Smith E M, Johnson H M, Blalock J E
J Immunol. 1983 Feb;130(2):773-6.
Human and mouse lymphocytes produced IFN-alpha and IFN-alpha/beta, respectively, when incubated with highly purified Staphylococcus aureus protein A (SPA). Maximum IFN induction occurred when lymphocytes were incubated with SPA at 250 to 500 micrograms/ml for 24 hr. The SPA induced-IFN were identified by neutralization of antiviral activity with specific antisera. A commercial preparation of SPA was found to induce both HuIFN-alpha and HuIFN-gamma, with the latter comprising over 90% of the antiviral activity. The SPA preparation that induced IFN-gamma was shown by SDS-polyacrylamide gel electrophoresis and an enzyme-linked immunosorbent assay to be contaminated with 5% S. aureus enterotoxin A (SEA), a potent T lymphocyte mitogen and IFN-gamma inducer. Preincubation of the commercial SPA with a specific antiserum to SEA blocked the induction of IFN-gamma and had no effect on IFN-alpha production. SEA is a very potent IFN-gamma inducer, effective at concentrations of 1 ng/ml or less. Thus, very minor contamination of SPA by SEA or other IFN-gamma inducers could be responsible for previous reports that SPA induces IFN-gamma in lymphocytes or that SPA behaves as a T cell mitogen.
当与高度纯化的金黄色葡萄球菌蛋白A（SPA）一起孵育时，人淋巴细胞和小鼠淋巴细胞分别产生α干扰素和α/β干扰素。当淋巴细胞与250至500微克/毫升的SPA孵育24小时时，干扰素诱导达到最大值。通过用特异性抗血清中和抗病毒活性来鉴定SPA诱导的干扰素。发现一种市售的SPA制剂可诱导人α干扰素和人γ干扰素，其中后者占抗病毒活性的90%以上。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和酶联免疫吸附测定法表明，诱导γ干扰素的SPA制剂被5%的金黄色葡萄球菌肠毒素A（SEA）污染，SEA是一种有效的T淋巴细胞有丝分裂原和γ干扰素诱导剂。用针对SEA的特异性抗血清对市售SPA进行预孵育可阻断γ干扰素的诱导，而对α干扰素的产生没有影响。SEA是一种非常有效的γ干扰素诱导剂，在浓度为1纳克/毫升或更低时有效。因此，SEA或其他γ干扰素诱导剂对SPA的极微量污染可能是先前报道SPA在淋巴细胞中诱导γ干扰素或SPA表现为T细胞有丝分裂原的原因。
