• Shaking phenomenon;
  • antispermatozoal antibodies;
  • serum IgA

ABSTRACT: Serum was obtained from a woman with a high (> 1000) titre of antispermatozoal antibody of IgA immunoglobulin class determined by the indirect immunobead test (IBT). It was found that the serum could sensitize normal sperm to give a strong shaking reaction in the semen-cervical mucus contact test (SCMCT). The capacity to induce shaking was retained after absorption of the serum with protein A-sepharose, but lost after absorption with rabbit antihuman IgA. The results therefore suggest that antispermatozoal antibodies of IgA class from serum can induce shaking, and are consistent with the possibility that the Fc fragment (rather than secretory component or J-chain) may be important for induction of shaking in the conventional SCMCT.