Enzyme-linked immunosorbent assay for measurement of antibodies against pneumococcal polysaccharide antigens: comparison with radioimmunoassay.

An enzyme-linked immunosorbent assay (ELISA) for measuring antibodies against each of 14 polysaccharides in contemporary pneumococcal vaccine is described, and the findings of tests of paired sera from vaccinated human subjects are compared with those obtained by radioimmunoassay. The findings were in very poor agreement, and this appears to be due to the lesser ability of the ELISA procedure to measure antibody of low avidity. The ELISA procedure described here is not considered to be a satisfactory substitute for radioimmunoassay for measuring antibody responses to pneumococcal vaccine.