Suarez S S, Oliphant G
Biol Reprod. 1982 Sep;27(2):473-83. doi: 10.1095/biolreprod27.2.473.
Unheated rabbit and human sera were found to induce acrosomal loss in rabbit spermatozoa, while similar concentrations of heated sera did not. In addition, human serum did not induce acrosomal loss when pretreated with antiserum to complement component C8, suggesting that acrosomal loss in unheated serum is caused by the membrane attack complex of complement. Human serum complement anaphylatoxins did not induce acrosomal loss, although they are known to induce exocytosis of secretory granules in other cell types. When incubated directly in human or rabbit sera, rabbit spermatozoa fixed complement; i.e., reduced the potential hemolytic activity of the sera. Fixation was suppressed by adding EGTA to reduce free calcium. This indicates that rabbit spermatozoa fix complement by initiating the classical pathway to complement activation. Initiation requires the presence of cell-bound immunoglobulins and the subsequent binding of complement component C1q. Immunoglobulins were detected in detergent extracts of washed ejaculated spermatozoa by a solid-phase radioimmunoassay, and the binding of 125 I-human C1q was detected on samples of living ejaculated spermatozoa. Seminal plasma was found to inhibit complement-induced hemolysis of erythrocytes. These results suggest that, in the absence of seminal plasma, spermatozoa may activate complement where it is present in the male or female tract.
未加热的兔血清和人血清可导致兔精子顶体丢失，而相似浓度的加热血清则不会。此外，用人补体成分C8抗血清预处理后的人血清不会导致顶体丢失，这表明未加热血清中的顶体丢失是由补体膜攻击复合物引起的。人血清补体过敏毒素不会导致顶体丢失，尽管已知它们可诱导其他细胞类型的分泌颗粒胞吐。兔精子直接与人或兔血清孵育时会固定补体，即降低血清的潜在溶血活性。添加乙二醇双乙醚二胺四乙酸（EGTA）以降低游离钙可抑制补体固定。这表明兔精子通过启动补体激活的经典途径来固定补体。启动需要细胞结合免疫球蛋白的存在以及随后补体成分C1q的结合。通过固相放射免疫测定法在洗涤后的射出精子的去污剂提取物中检测到免疫球蛋白，并在活的射出精子样本上检测到125I-人C1q的结合。发现精浆可抑制补体诱导的红细胞溶血。这些结果表明，在没有精浆的情况下，精子可能会激活存在于男性或女性生殖道中的补体。
