Evaluation of humoral responsiveness in children.

The evaluation of postvaccine antibody responses can provide a reasonably convenient and useful adjunct to the evaluation of possible humoral immune dysfunction syndromes. In patients whose clinical history is suspicious for an antibody deficiency syndrome, such studies can document normal antibody responsiveness. On the other hand the wide age-dependent variation in antibody responses makes careful interpretation necessary in concluding that a patient falls outside the "normal" pattern of antibody responsiveness. Finding a patient well below the mean values for age for multiple vaccines in concert with an appropriate clinical history would strongly suggest an abnormality of immune regulation. At this time the finding of abnormal antibody responses does not always imply that intervention with immunoglobulin therapy is indicated or that it would lead to improvement in clinical symptoms. It might help justify prophylactic antibiotic programs, however, similar to those used for recurrent otitis media. Interpretation of antibody responses in children younger than 2 years of age is probably hazardous since many patients may have relative retardation in their normal development of polysaccharide antibody responsiveness. Such patients usually develop a normal response as they grow older and do not need long term therapy. Until new technologies for measuring immune competence are developed, the above-mentioned measures of humoral immunity, when combined with clinical judgment, should be adequate to guide clinical decision-making in most cases.