Measurement of group A streptococcal M-type antibodies by enzyme-linked immunosorbent assay and comparison between the M-type and T-type antibodies.

Abstract

Group A streptococci were isolated from throat-swabs once a month from January, 1985 to March, 1990. The subjects were school aged children accommodated in an institution because of weak physical condition or chronic diseases. Serum immunoglobulin M (IgM) and G (lgG) antibodies were measured by an enzyme-linked immunosorbent assay, using group A streptococci (type M-4, M-6 and M-12) as antigens.

The results are summarized as follows:

The highest levels of IgM and IgG antibodies were obtained with antigen concentrations of 0.5 to 1.0μg/ml. The antigens at these levels were type-specific. When M-type antibodies were compared with T-type, the levels of M-type antibodies were eight times as high as those of T-type antibodies in both IgM and IgG M-type antibodies. M-type antibodies continued to exist in children in whom T-type antibodies disappeared. We confirmed the survival of M-type antibodies to be longer than T-type antibodies.