[Natural immunity to Haemophilus influenzae type b. ELISA study of the distribution of IgG, IgG1 and IgG2 in France and Africa].

A Haemophilus influenzae type b capsular polysaccharide-tetanus toxoid conjugate vaccine will be released for use in infants in developing and industrialized countries in the near future. This prompted a comparative study of the natural immunity of mothers and passive immunity of their newborns in France and Africa. An ELISA method capable of discriminating immunoglobulin classes and subclasses was used. Monoclonal antibodies were used to determine titers of IgG1 and IgG2 antibodies. Because capsular polyribose ribitol phosphate does not bind readily to polystyrene, the plate was coated with streptavidine which bound to biotin linked to the antigen. Antibody titers were found to be identical in French and African study groups. Both IgG1 and IgG2 antibodies were found, often with higher titers for the latter. Both subclasses were found in cord blood of French and African children.