Genes associated with the G2m(23) immunoglobulin allotype regulate the IgG subclass responses to Haemophilus influenzae type b polysaccharide vaccine.

We determined whether genes associated with the G2m(23) allotype, a genetic marker on IgG2 molecules, influence the subclass composition of the antibody response to Haemophilus influenzae type b polysaccharide vaccine. After immunizing 70 white adults, the geometric means (GMs) of the total, IgG, IgG1, and IgG2 antibody concentrations increased approximately 10-fold over preimmunization concentrations. There was no significant difference in the GMs of the total, IgG, or IgG1 antibody concentrations in postimmunization sera from subjects positive versus those negative for G2m(23). Adults positive for G2m(23) had a GM IgG2 concentration more than threefold higher than that of negative subjects (P less than .001). The antibody responses of 61 Amish adults immunized with type b polysaccharide vaccine were also analyzed. Those adults positive for G2m(23) had a higher GM serum IgG2 response to capsule than did those who were negative (P less than .01). These data indicate that genes associated with the G2m(23) locus regulate the IgG subclass composition of the antibody response to H. influenzae type b polysaccharide vaccine.