A radioimmunoassay for antibody to pneumococcal polysaccharides.

A radioimmunoassay for type specific pneumococcal polysaccharides is described. This involves obtaining specific polysaccharides from culture supernatants by precipitation with ethanol saturated with potassium acetate, and then after further purification labelling the tyraminated polysaccharide with 125 iodine. The radioimmunoassay itself is a standard ammonium sulphate precipitation technique (Farr assay) using IgG myeloma protein as a carrier. We have found that measuring antibodies after test immunization with a polyvalent pneumococcal vaccine is a useful aid in diagnosing functional antibody deficiency.