Noriyuki Yamasaki

Direct Production of the Fab Fragment Derived From the Sperm Immobilizing Antibody Using Polymerase Chain Reaction and cDNA Expression Vectors

PROBLEM: Sperm immobilizing antibodies cause infertility mainly through complement dependent sperm immobilization. To analyze any effect of sperm immobilizing antibody on fertilization, we had already established cell lines that secrete IgM monoclonal antibody (MAb H6‐3C4) and IgG monoclonal antibody (MAb EnBCMGS). The latter was a class‐switched recombinant IgG antibody that shares the same variable region as MAb H6‐3C4. The biological effects of the IgG antibody were also reported previously to eliminate sperm immobilizing or sperm agglutinating activities. However, the method of chemical digestion of IgG had some disadvantage to prepare the purified Fab fragment stably and in large quantities. This time we report a unique method to obtain the recombinant Fab fragments (Fab EnBCMGS) using polymerase chain reaction (PCR) and cDNA expression vectors.

Stable production of recombinant human sperm immobilizing antibody using cDNA expression vectors.

PROBLEM: Sperm immobilizing antibodies present in sterile women may be one of the principal causes of immunological infertility. We already established cell lines that secrete recombinant human IgG sperm immobilizing antibody using class‐switched (from IgM to IgG) genomic immunoglobulin genes. However, these transfectants produced a small quantity of antibody and required continuous use of a medium with selective reagents. We have now constructed cell lines that stably secrete the antibody in large quantities using immunoglobulin cDNAs and cDNA expression vectors.