Weis J J, Law S K, Levine R P, Cleary P P
J Immunol. 1985 Jan;134(1):500-5.
The previous finding that phagocytosis-resistant M+ group A streptococci bear quantities of C3 which are sufficient for phagocytosis of their M- derivatives was investigated at two levels. It was first established that the C3 associated with M+ streptococci was not able to promote adherence to cells bearing the complement receptors CR1 and CR3 under conditions in which M- streptococci readily attached. The molecular form of C3 bound to M+ and M- streptococci was then defined by adding 125I-C3 to serum used for opsonization. C3 eluted from the bacteria by chaotropic and hydrolytic agents was analyzed by SDS-PAGE, and revealed that both cell types bound the opsonic forms of C3, C3b, and iC3b. Furthermore, approximately 80% of the C3b and iC3b associated with both cell types was covalently bound to a surface component, although most of the C3 bound to M+ streptococci was detergent-extractable, whereas greater than 50% of that bound to M- streptococci was not. These findings demonstrate that the M+ surface is interfering with the receptor binding of deposited C3b and iC3b, and that this contributes to resistance to phagocytosis by these organisms.
先前的研究发现抗吞噬的M+ A群链球菌携带的C3量足以使其M-衍生物被吞噬，本研究从两个层面进行了调查。首先确定，在M-链球菌易于附着的条件下，与M+链球菌相关的C3不能促进其与携带补体受体CR1和CR3的细胞的黏附。然后通过向用于调理作用的血清中添加125I-C3来确定与M+和M-链球菌结合的C3的分子形式。用离液剂和水解剂从细菌中洗脱的C3通过SDS-PAGE进行分析，结果显示两种细胞类型均结合了C3的调理形式C3b和iC3b。此外，与两种细胞类型相关的C3b和iC3b中约80%共价结合到一种表面成分上，尽管与M+链球菌结合的大部分C3可被去污剂提取，而与M-链球菌结合的C3中超过50%不能被提取。这些发现表明，M+表面干扰了沉积的C3b和iC3b的受体结合，这有助于这些生物体抵抗吞噬作用。
