Proportional absorption. A method for determination of the relative specificity of antisera prepared against cells.

Antisera prepared against a complex of antigens such as a tissue cell may produce a mixture of antibodies of different specificities, affinities and types. Proportional absorption permits determination of the comparative specificity of such antisera. It is performed by absorbing the antisera with an amount of absorbent proportional to the initial content of (usually undesired) antibody to this absorbent; the potencies of desired and undesired antibodies are then separately determined. The method has been used to determine the specificity of a conventionally raised rabbit anti-mouse leukaemia serum, relative to one prepared with leukaemia cells admixed with rabbit antiserum against normal mouse lymphocytes (to block normal antigen sites on the leukaemia cell inoculum). The latter antiserum was cells as compared to normal splenic lymphocytes.