In experimental animals, immune responses to certain
antigens are regulated by
immunoglobulin allotype-linked genes. In an effort to detect such genes in humans, we examined the antibody responses of 74 healthy children with different Km(1) or Gm(23) allotypes to a Haemophilus influenzae type b
vaccine (type b
polysaccharide capsule-
pertussis vaccine). The anticapsular antibody responses of black or white children with the Km(1) allotype were 4.6- to 9.5-fold higher than those of children who lacked this determinant (P less than 0.004). No significant differences were found in antibody response with respect to the
Gm(23) allotype. The frequencies of Km(1) and Gm(23) also were examined in 170 patients with
Haemophilus meningitis, 71 patients with
epiglottitis, and 173 control children. Km(1) was detected less frequently in black patients with
meningitis (38%) than in those with
epiglottitis (81%, P less than 0.002) or in controls (66%, P less than 0.0007). The relative risk of
meningitis thus was 3.2-fold lower among black children with the Km(1) allotype than in those who lacked this allotype (odds ratio = 0.3, 95% confidence interval 0.2 to 0.6). However, the risk of
meningitis was not decreased in white children with the Km(1) allotype (odds ratio = 1.0). There were no significant differences in the frequency of Gm(23) among the patient groups and controls. The Km(1) allotype but not the Gm(23) thus defines a subpopulation of children of both races who are high responders to this
vaccine, and black children but not white children with the Km(1) allotype are at decreased risk of developing
Haemophilus meningitis. These data indicate that in blacks, genes associated with Km(1) may affect immune response to a prototype type b
Haemophilus vaccine, and perhaps interact with another factor related to race to affect susceptibility to
Haemophilus meningitis.