Siblings of patients with Haemophilus meningitis have impaired anticapsular antibody responses to Haemophilus vaccine

Variation between Populations in the Innate Immune Response to Vaccine Adjuvants

The success of the World Health Organization recommended “Expanded Program of Immunization” (EPI) and similar regional or national programs has been astounding. However, infectious threats currently not covered by these programs continue to infect millions of infants around the world. Furthermore, many infants do not receive existing vaccines either on time or for the required number of doses to provide optimal protection. Nor do all infants around the world develop the same protective immune response to the same vaccine. As a result approximately three million infants die every year from vaccine preventable infections. To tackle these issues, new vaccines need to be developed as well as existing ones made easier to administer. This requires identification of age-optimized vaccine schedules and formulations. In order to be most effective this approach will need to take population-based differences in response to vaccines and adjuvants into account. This review summarizes what is currently known about differences between populations around the world in the innate immune response to existing as well as new and promising vaccine adjuvants.

Genetic variation in the response to vaccination

Vaccines are the most powerful means to prevent and diminish the burden of infectious disease. However, there are limitations to their use: vaccines are not yet available for all infectious diseases (including human immunodeficiency virus and respiratory syncytial virus), they sometimes lack efficacy, the response to vaccination is limited by maternal antibodies in very young infants, and the response to vaccination is variable or may even be absent in some individuals. This review focuses on genetic factors that determine the variable response to vaccination. The highly polymorphic human leukocyte antigen system, which is involved in antigen presentation, has been researched most in this aspect, and clearly affects the response to vaccination. Other, but less polymorphic pathways involved are the Toll-like receptor pathway, which is involved in antigen recognition and stimulation of the immune system, and the cytokine immunoregulatory network. The heritability, or the proportion of total variance that is due to additive genetic factors, appears to be particularly large for vaccine-induced antibody responses in young infants compared with cell-mediated responses and antibody responses in older, immunologically more mature individuals. Both antibody and cell-mediated responses are not only affected by loci within, but also strongly by loci outside the human leukocyte antigen system. Because most genes that are important in influencing immune responses to vaccination are still unknown, clearly more work is required. A better understanding of the factors that determine an effective response to vaccination may lead to the identification of specific genes and pathways as targets for the development of novel more uniformly effective vaccines.

Influence of genetic and environmental factors on the immunogenicity of Hib vaccine in Gambian twins

The differences in incidence rates of Haemophilus influenzae type b disease and the variation in Hib conjugate vaccine efficacy achieved among different ethnic groups suggest genetic influences on the immune response to Hib vaccine. The serum anti-PRP antibody concentration of 43 monozygotic (MZ) and 147 dizygotic (DZ) twin pairs in the Gambia was measured using a standardised Hib ELISA. Intrapair correlations for MZ and DZ twin pairs were compared and heritability in antibody responses to Hib conjugate vaccine was estimated to be 51% (95% CI: 32-66%), indicating a significant genetic contribution in the response. We conclude that genetic factors may be involved in the variation in immune response to Hib vaccine observed in different populations and may contribute to cases of vaccine failure.

Serum IgG2 level, Gm(23) allotype and FcgammaRIIa and FcgammaRIIIb receptors in refractory periodontal disease

The purpose of this investigation was to compare the levels of serum IgG2, the frequency of detection of Gm(23)-negative allotype and frequency of detection of FcgammaRIIa and FcgammaRIIIb receptor haplotypes in 32 refractory, 54 successfully treated and 27 periodontally healthy individuals. Refractory subjects showed mean full mouth attachment loss and/or >3 sites with attachment loss >2.5 mm within 1 year after both scaling and root planing, and surgery plus systemically administered tetracycline. Successfully treated subjects showed mean attachment level gain and no sites with attachment loss >2.5 mm 1 year post-therapy. Periodontally healthy subjects exhibited no pocket depth or attachment level >3 mm, and no evidence of progressing disease during 1 year of monitoring. Blood was obtained from each subject at baseline. Serum IgG2 and Gm(23) allotype were determined using radial immunodiffusion. DNA was extracted from whole blood and the FcgammaR genotypes determined using PCR and allele specific oligonucleotide probes. Significance of differences among clinical groups were sought using the Kruskal-Wallis or chi-square tests. Associations between 2 or more variables were tested using regression analysis. Refractory subjects exhibited higher mean attachment loss and pocket depth than successfully treated or periodontally healthy subjects. Smoking status did not differ significantly among groups. No significant differences in serum IgG2 levels and frequency of detection of Gm(23)-negative allotype were observed among the clinical groups. Serum IgG2 level was positively associated with the number of serum antibody responses to subgingival species (r=0.51, p<0.001). Subjects with the Gm(23)-negative allotype exhibited lower mean levels of serum IgG2 (3.06+/-0.3 versus 3.9+/-0.2, p<0.01) and mean number of serum antibodies to subgingival species (17.7+/-1.7 versus 23.3+/-1.4, p<0.05) than allotype positive individuals. No significant differences in FcgammaR haplotype distribution were observed among the 3 clinical groups. Associations of serum IgG2 level, Gm(23) allotype, FcgammaRIIa and FcgammaRIIIb receptor haplotypes and smoking status were weakly related or not related to clinical status. This lack of relationship may have been due to a reality of no relationship, or the inadvertent pooling of subjects where these factors were of primary importance with subjects in whom these factors played a less important role.

Serum and salivary antibody responses to non-capsular Haemophilus influenzae antigens in children with meningitis and epiglottitis

Serum IgG, IgA and IgM antibody and salivary IgA antibody concentrations to non-capsular Haemophilus influenzae antigens were measured in 13 children with H. influenzae type b meningitis and in 15 children with epiglottitis. Most had detectable serum IgG and IgM antibody at presentation but significantly fewer patients with meningitis had serum IgA antibody at presentation (P less than 0.05). Serum antibody concentrations had risen significantly by 3 weeks after presentation in patients with epiglottitis only. Convalescent serum IgG antibody concentrations against these antigens were higher in younger children with epiglottitis. Salivary IgA antibody to H. influenzae was detectable at presentation in all children with epiglottitis and in 12 of 13 with meningitis. Salivary antibody concentrations did not differ significantly between the two patient groups at presentation, although patients with meningitis had higher salivary IgA antibody concentrations than 10 children of similar age with bronchiolitis (P less than 0.02). There was no association between the presence of salivary antibody and low concentrations of convalescent serum antibody. The rise in convalescent serum antibody concentrations to non-capsular H. influenzae antigens only in children with epiglottitis is similar to findings for antibody to capsular polysaccharide. However, this rise was greater for IgG in younger patients, and the low titre of convalescent serum antibody in patients with meningitis was not associated with higher titres of IgA antibody in secretions as described by others for polysaccharide antibody. These findings suggest that the poor serum antibody response to these antigens in patients with meningitis is independent of age and is not due to mucosal induction of systemic tolerance.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic factors in Haemophilus influenzae type b disease susceptibility and antibody acquisition

Because Alaskan Eskimos have the greatest known endemic risk of Haemophilus influenzae type b (Hib) disease and represent a comparatively homogeneous population, we selected this population to evaluate the presence or absence of an association of 35 genetic markers (alleles or allotypes) at 12 chromosomal loci with susceptibility to both invasive Hib disease risk and level of Hib anticapsular antibody. We studied nearly all Alaskan Eskimo children who had had invasive Hib disease between 1971 and 1982 in southwestern Alaska (n = 103) and an equivalent number of controls matched for age, race, and village of residence, and verified not to have had proved or suspected Hib disease. We found no significant associations with Hib disease for the single alleles of HLA-A, -B, -C, -DR, Gm, Km, Am, Kidd, MNSs, ABO, esterase D, or glutamate pyruvate transaminase loci. However, we observed a significant interaction of two loci, Gm(a;..;g,s,t) allotype and HLA-DR8 (P = 0.002), with increased Hib disease susceptibility, and an interaction of the same Gm allotype and HLA-DR5 with decreased disease susceptibility (P = 0.01). We also compared the level of anticapsular antibody to Hib with each genetic marker and two-locus interactions, but no genetic association with antibody level was found. We conclude that some genetic factors contribute to the susceptibility to invasive Hib disease in this population.

Correlation of the Km(1) immunoglobulin allotype with anti-polysaccharide antibodies in Caucasian adults

Km allotype antigens are serologic markers expressed on kappa light chains of human immunoglobulins. To determine whether th Km phenotype of an individual is related to his ability to make antibodies to polysaccharide antigens, we correlated the Km allotypes of 129 healthy caucasian adults with the concentrations of specific antibodies to three bacterial polysaccharide antigens after immunization. The 14 individuals expressing the Km(1) allotype had lower concentrations of IgG, IgM, and IgA antibodies by enzyme-linked immunosorbent assay and total antibody by radioimmunoassay to Haemophilus influenzae type b and Neisseria meningitidis group C capsular polysaccharides when compared with the 115 Km(1) negative individuals. The Km-associated differences in H. influenzae type b and N. meningitidis group C antibody concentrations were confined to kappa light chain-containing antibody (P = 0.029 and 0.003, respectively). Similarly, the Km(1) positives had slightly lower kappa chain-containing Ig than the Km(1) negatives (P = 0.079). We conclude that genes in or near the kappa light chain locus play a role in the regulation of kappa-containing antibody production to some bacterial polysaccharides and perhaps to other antigens.

Primary invasive Haemophilus influenzae type b disease: a population-based assessment of risk factors

We performed a population-based case-control study of risk factors for primary invasive Haemophilus influenzae type b (Hib) disease in metropolitan Atlanta from July 1, 1983, through June 30, 1984. Active surveillance identified 102 cases in children less than 5 years of age, 89 of whom lived in households with telephones. We used random digit dialing to select 530 controls who were postmatched to cases by age. Multivariate analysis showed a significant association between Hib disease and two independent exposure factors, household crowding (odds ratio (OR) 2.7, 95% confidence limits (CL) 1.3 to 5.6) and day-care attendance. For day-care attendance, relative risk was highest in 2- to 5-month-old infants (OR 17.7, 95% CL 5.8 to 54.4) and declined to 9.4 (4.3 to 20.9) at ages 6 to 11 months, 5.0 (2.7 to 9.3) at 12 to 23 months, 2.7 (1.3 to 5.5) at 24 to 35 months, and 1.4 (0.5 to 4.0) in 36- to 59-month-old children. Fifty percent of all invasive Hib disease that occurred during the study period was attributable to exposure to day-care; the attributable risk for household crowding was 18%. Dose-response effects were observed for hours per week of day-care attendance and extent of household crowding. Breast-feeding was protective for infants less than 6 months of age (OR 0.08, 95% CL 0.01 to 0.59). After controlling for socioeconomic and other confounding factors, we could demonstrate no effect of black race on cumulative risk of invasive Hib disease. Our study defines high-risk groups and provides a population-based model of the interrelationship between risk factors associated with invasive Hib disease.

Uridine monophosphate kinase and susceptibility to invasive Haemophilus influenzae type B disease

A polymorphic genetic variant of the pyrimidine pathway enzyme, uridine monophosphate kinase-3 (UMPK-3), was positively associated with invasive Hib disease. All UMPK 3-3 homozygotes in this study were Hib cases, and we found that in cases and controls, there was no difference between UMPK phenotype and serum levels of total Hib antibody as measured by radioimmunoassay. This suggests that UMPK-3 may play a role in mediating the non-humoral immunity to Hib. However, unlike other enzyme variants in the nucleoside synthesis pathways which result in syndromes of severe immunodeficiency, this gene appears to confer a more subtle disease susceptibility. Thus, the UMPK-3 allele, although rare in Caucasians, is associated with an increased risk of invasive Hib infection in Alaskan Eskimos.

Correlation of serum immunoglobulin subclass concentrations with antibody responses of children to immunization with Haemophilus influenzae type b polysaccharide-pertussis vaccine

Children less than 24 months of age respond poorly to immunization with the capsular polysaccharide of Haemophilus influenzae type b. Because human antibodies to polysaccharide antigens are relatively restricted to IgG2, a late-maturing subclass, we examined the relationship between serum subclass concentrations and anticapsular antibody responses of 41 healthy children, 9 to 38 months of age, following immunization with type b polysaccharide mixed with pertussis vaccine. Both total and IgG anticapsular antibody responses correlated significantly with preimmune serum concentrations of IgG2 but not with those if IgG1. This correlation was age dependent, however, and after the effect of age was removed by partial correlation, the correlation between anticapsular antibody responses and serum IgG2 concentrations was no longer significant. These findings indicate that the ability to respond to this vaccine coincides with maturation of the ability to secrete immunoglobulin of the IgG2 subclass; however, individual variation in IgG2 that is independent of age does not correlate with antibody response to the type b polysaccharide.

Uridine monophosphate kinase 3: a genetic marker for susceptibility to Haemophilus influenzae type B disease

Alaskan Eskimos have the highest known prevalence of invasive Haemophilus influenzae type b (Hib) disease, primarily meningitis, affecting 1-5% of all children in the first two years of life. In this population a polymorphic genetic variant of the pyrimidine pathway enzyme, uridine monophosphate kinase-3 (UMPK-3), was found to be positively associated with invasive Hib disease (relative risk 3.3) and a tendency towards a younger age at onset of illness. There was no difference in levels of naturally acquired Hib anticapsular antibody between persons with Hib disease and healthy controls in this population. This suggests that UMPK-3 may have a role in mediating non-humoral immunity to Hib. However, unlike other enzyme variants in the nucleoside synthesis pathways which result in syndromes of severe immunodeficiency, this gene appears to confer a more subtle disease susceptibility.

Correlation between G2m(n) immunoglobulin allotype and human antibody response and susceptibility to polysaccharide encapsulated bacteria

To determine whether genetic factors influence the human antibody response to polysaccharides, we correlated Ig allotypes with the concentrations of antibody to 14 bacterial capsular antigens in 130 actively immunized Caucasian adults. The 88 individuals possessing G2m(n), an allotype antigen of IgG2 subclass heavy chains, had significantly higher postimmunization antibody levels to Haemophilus influenzae type b (Hib) and 8 of 11 pneumococcal types (P less than 0.05) than the 42 lacking this antigen. For Hib, pneumococcus type 14, and meningococcus group C, an increased response was observed in IgG class but not in IgM or IgA classes of antibody. The G2m(n) positive individuals also had higher preimmunization antibody levels to most polysaccharide antigens. Total IgG2 concentrations were correlated with the mean postimmunization antibody concentrations to pneumococci (P = 0.005), but this correlation was independent of G2m(n) by multiple regression analysis. To determine if the lack of G2m(n) was associated with increased susceptibility to infection, we compared the frequencies of various Ig allotypes in 98 children infected with Hib and 98 matched controls. Caucasian children with Hib infections other than epiglottitis were significantly more likely to lack the G2m(n) allotype than controls (P less than 0.05). G2m(n) negative Caucasian children less than or equal to 18 mo old have a 5.1-fold higher risk of nonepiglottitic Hib infections than G2m(n) positive children (P less than 0.01). We conclude that allotypic variants of the gamma-2 heavy chain genes, or genes in linkage equilibrium with them, exert a regulatory influence on the caucasian antibody response to a variety of immunologically distinct bacterial polysaccharide antigens. Young Caucasian children of the low responder phenotype, i.e., those lacking the G2m(n) allotype, are genetically predisposed to Hib and perhaps other bacterial infections.

Response to immunization with Haemophilus influenzae type b polysaccharide-pertussis vaccine and risk of Haemophilus meningitis in children with the Km(1) immunoglobulin allotype

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.

Immunogenicity of Haemophilus influenzae type b polysaccharide--diphtheria toxoid conjugate vaccine in adults

The capsular polysaccharide of Haemophilus influenzae type b is a poor immunogen in human infants. In an attempt to enhance immunogenicity, this polysaccharide was covalently coupled to diphtheria toxoid and the conjugate tested as a vaccine in adult volunteers. Two injections of PRP-D vaccine were given, separated by one month. The anti-PRP antibody responses in this group were compared with those in a group receiving a comparable dose (20 micrograms) of conventional PRP vaccine. Both vaccines were well tolerated. A single injection of PRP-D was significantly more immunogenic than PRP, eliciting higher serum concentrations of total anti-PRP antibody 1 month later (geo means of 248 and 62 micrograms/ml, respectively; P less than 0.001). In addition, higher concentrations of IgG anti-PRP antibody were observed in the PRP-D group (P less than 0.001). One month after reinjection of vaccine, subjects receiving PRP-D showed a small but significant decline in total antibody (P = 0.03), whereas the serum antibody concentrations in the group that received PRP remained unchanged. At 12 months, the antibody concentrations of the two groups were not significantly different. Bactericidal activity and passive protection activity (infant rat model) were tested in pooled sera from the three highest and three lowest responders in each vaccine group; both PRP and PRP-D vaccines induced biologically active anti-PRP antibody. Thus PRP-D was found to elicit biologically active serum antibody and to be more immunogenic in adults than PRP vaccine; however, the duration of higher concentrations of antibody was transient.

A review of Haemophilus influenzae infections in Cambridge 1975-1981

Invasive Haemophilus influenzae infections diagnosed in Cambridge between January 1975 and December 1981 are reviewed. Altogether, 81 sites in 77 patients were infected. Of these patients, 41 had meningitis, 20 epiglottitis, 8 bone or joint infections (2 with concurrent meningitis), 4 cellulitis, 5 pneumonia (2 with concurrent epiglottitis) and 3 septicaemia in the absence of documented localised infection. Most patients (88%) were children less than 5 years of age. Only 8 adults with such infections were identified. Of these, 6 had an identifiable predisposing condition. The incidence of meningitis was 18 cases per 100 000 children less than 5 years of age. There were 3 deaths. Of the strains of H. influenzae isolated, 16% were ampicillin-resistant. The unusual age-specific incidence of epiglottitis and the incidence of deafness after meningitis are emphasised.

Interactive effect of genes associated with immunoglobulin allotypes and HLA specificities on susceptibility to Haemophilus influenzae disease

Genes associated with immunoglobulin (Ig) allotype determinants are important in regulation of immune responses to bacterial polysaccharides. Furthermore, loci associated with Ig allotypes have been reported to interact with those associated with the major histocompatibility complex and affect susceptibility to certain diseases. In the present study we determined the frequencies of certain Gm phenotypes in patients with Haemophilus meningitis or epiglottitis and in controls. HLA-A, -B and -DR specificities had previously been determined in the majority of these subjects. Although no Ig phenotype was associated with increased or decreased relative risk of disease, the frequencies of several combinations of HLA specificities and Ig phenotypes were significantly different from those of controls. Thus, for subjects with the Gm phenotype (1, 3, 17; 23; 5, 13, 21), the risk of Haemophilus meningitis or epiglottitis was lower in individuals with HLA-B5 than in those without this specificity (odds ratio less than 0.1, P less than 0.004). In contrast, for subjects with the closely related Gm phenotype differing only by the absence of Gm(23), (1, 3, 17; ; 5, 13, 21), the risk of disease was higher in those with HLA-DR3 than in individuals who lacked DR3 (odds ratio = 11.0, P = 0.02). Although the present data require confirmation in an independent sample, they suggest that complex interactions between genes at two independent loci controlling HLA and Ig allotypes, respectively, may affect susceptibility to Haemophilus disease.

Antibody-dependent alternative pathway killing of Haemophilus influenzae type b

The bactericidal activities of human complement and human antibody directed against specific Haemophilus influenzae type b cell surface determinants were investigated. Strain Eagan, a laboratory isolate, and strain Kn, a clinical isolate, were used as the test organisms and gave qualitatively similar results. In the absence of antibody, both isolates were resistant to killing by 60% agammaglobulinemic serum (AGS) containing normal complement levels. The addition of affinity-purified immunoglobulin G anticapsular antibody was bactericidal with 15% AGS as the complement source. Bactericidal activity was also demonstrated with this antibody when the complement source was AGS-Mg-EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid], C2-deficient human serum (alternative complement pathway), or AGS in which factor D and properdin had been selectively inactivated (classical pathway). Immunoglobulin G fractions from a human serum pool or from serum from an adult who had recovered from H. influenzae type b (Kn) sepsis were absorbed to remove anticapsular antibody. The absorbed fractions containing noncapsular antibodies also activated complement-dependent bactericidal activity. But, in contrast to the results with anticapsular antibody, noncapsular antibodies did not elicit alternative pathway bactericidal activity. Incubation of cells of H. influenzae type b in C2-deficient serum or AGS-Mg-EGTA did not cause complement consumption (total hemolytic complement and C3). The addition of immunoglobulin G anticapsular antibody (but not noncapsular antibody) increased consumption of total complement and C3, paralleling the results of the bactericidal assays. These studies demonstrated an absolute requirement for anticapsular antibody in alternative pathway activation and killing of H. influenzae type b.(ABSTRACT TRUNCATED AT 250 WORDS)