Evaluation of test immunisation in the assessment of antibody deficiency syndromes.

Antibody responses after immunisation with pneumococcal polysaccharide did not correlate with the severity and frequency of infections in 22 patients with severe hypogammaglobulinaemia, when these were measured by a Farr radioimmunoassay. Five "healthy" patients with severe hypogammaglobulinaemia not only failed to make antipneumococcal polysaccharide antibody, when measured by radioimmunoassay, but also had very low or unrecordable antibody responses to Escherichia coli and failed to produce antibody when immunised with tetanus toxoid. Some of these subjects, however, did make small amounts of IgM antipneumococcal polysaccharide antibody when this was measured by an enzyme linked immunosorbent assay, while others retained some ability to produce IgM or IgA or both in their saliva. These findings show that the measurement of serum antibody responses after immunisation, with the possible exception of IgM antibodies to polysaccharides, is unlikely to be helpful in assessing the requirement for gammaglobulin replacement therapy in patients with hypogammaglobulinaemia.