Kearney R, Halliday W J
Immunology. 1970 Oct;19(4):551-60.
The nature of two distinct anti-pneumococcal antibodies of mice has been further investigated. These antibodies, produced after the injection of purified SIII (the capsular polysaccharide of Type III), were examined for their serological properties and for their protective potency . The first anti-SIII antibody, distinguished by its ability to agglutinate antigen-coated erythrocytes, was not only unable to lyse these erythrocytes (with complement), but it protected them against lysis by the other antibody, because of its high affinity for the antigen. This haemagglutinating antibody did not precipitate soluble antigen, was of the IgA class, and could protect mice against challenge with virulent pneumococci. It was produced by mice given small doses (0.1 μg) of SIII, but not by mice given 50 μg. These latter were susceptible to pneumococcal challenge. The second antibody, which was haemolytic and precipitating but not haemagglutinating, had a comparatively low affinity for the antigen: thus it was not detectable when mixed with the first antibody, especially if the test erythrocytes were inadequately sensitized. This haemolytic antibody was of the IgM class. It was found in high titre in mice given 50 μg of SIII, but did not protect them against challenge.
对小鼠体内两种不同的抗肺炎球菌抗体的性质进行了进一步研究。这些抗体是在注射纯化的SIII（III型荚膜多糖）后产生的，对其血清学特性和保护效力进行了检测。第一种抗SIII抗体以其凝集抗原包被红细胞的能力为特征，它不仅不能（借助补体）裂解这些红细胞，而且由于其对抗原的高亲和力，还能保护它们免受另一种抗体的裂解。这种血凝抗体不能沉淀可溶性抗原，属于IgA类，并且可以保护小鼠免受强毒肺炎球菌的攻击。它是由给予小剂量（0.1μg）SIII的小鼠产生的，但给予50μg SIII的小鼠则不产生。后者易受肺炎球菌攻击。第二种抗体具有溶血和沉淀作用，但无血凝作用，对抗原的亲和力相对较低：因此，当与第一种抗体混合时，尤其是在测试红细胞致敏不足的情况下，它无法被检测到。这种溶血抗体属于IgM类。在给予50μg SIII的小鼠中发现其效价很高，但不能保护它们免受攻击。
