A sedimentation pattern technique for measuring conglutination: its application to demonstrating immunoconglutinins to C'4

Abstract

The usual method of measuring the conglutination phenomenon is to use a centrifugation and resuspension technique to assess the clumping of alexinated cells. This method is designed only to detect powerful clumping and immunoconglutinins measured in this way have always been found to react with fixed C′_3a.

A disadvantage of this method is that only antibodies to complement-antigens present in large amount on the alexinated cell will be detected. This may explain why immunoconglutinins (I-Ks) to other complement components have not been found.

A method of measuring I-Ks by a sedimentation pattern has been devised. A macroglobulin fraction of an antiserum to purified Forssman hapten is used to sensitize the erythrocyte. This is complement-fixing much beyond its agglutination titre and is almost free of reactivity with rheumatoid factors. Guinea-pig complement is used to alexinate and various defined intermediates have been tested—namely EA (sensitized sheep cells) EAC′₄, EAC′₁₄₂, EAC′_1423a, EAC′_43a.

It has been found that immunoconglutinins reacting with EAC′₄ are commonly found in human sera. Reaction with EAC′₄ is usually as good as and sometimes much better than with EAC′₁₄₂.

However the reactivity of most I-Ks with fixed C′_3a has been confirmed as has the exclusive reactivity of bovine conglutinin with fixed C′_3a.

Some level of I-K has been found in all the human sera tested. Particularly high levels have been found in trypanosomiasis.