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

Immunologic and clinical status of blood donors with subnormal levels of IgG2

To determine the immunologic and clinical status of individuals from a general population with subnormal levels of IgG2, we prospectively studied 37 of 312 blood donors with low IgG2 levels identified among 8015 donors. We examined (1) G2m(23) allotypes, (2) levels of other IgG subclasses and immunoglobulin classes, (3) composition of peripheral leukocyte populations, (4) responses to two carbohydrate antigen vaccines, (5) in vitro secretion of IgG subclasses by isolated lymphocytes after mitogen stimulation, and (6) clinical histories. We found that most (90%) individuals with subnormal IgG2 levels had G2m(23)- allotypes, whereas only 30% of the unselected donors had G2m(23)-. When individuals were separated according to their G2m(23) allotype, we found that IgG2 "normal" range for individuals with G2m(23)- allotype is 35% lower than for individuals with G2m(23)+ allotype. Individuals who had G2m(23)- allotype and had IgG2 levels greater than or equal to 0.8 but less than 1.3 gm/L had no other immunologic abnormalities. In contrast, the individuals with G2m(23)+ allotype and with IgG2 levels less than 1.3 gm/L and the individuals with G2m(23)- allotype and with IgG2 levels less than 0.8 gm/L often had additional immunologic abnormalities, including IgA and/or IgG4 deficiency and decreased in vitro expression of IgG2 subclass. None of these individuals had a clinical history remarkable for recurrent infections. Thus, subnormal IgG2 levels interpreted with G2m(23) corrected normal ranges may be a marker of other immunologic abnormalities but taken alone probably have little clinical significance in a general healthy population.

Lack of the G2m(n) allotype in IgG subclass deficiency, in IgG2 deficiency together with lack of G1m(a) and G3m(g), and in IgG3 deficiency together with lack of G1m(f) and G3m(b)

Lack of G2m(n) was demonstrated in both IgG2-deficient and IgG3-deficient Caucasian patients. Lack of G2m(n) or G2m(",") was found together with homozygosity for both G1m and G3m allotypes as the dominant finding, i.e. for IgG2-deficient patients together with G1m (f,f) and G3m(b,b), constituting the Gm(f,",b) phenotype, and for IgG3-deficient patients together with G1m(a,a) and G3m(g,g), constituting the Gm(a,",g) phenotype. The group with IgG2 deficiency and the selected patients with the Gm(f,",b) phenotype expressed characteristically very low or undetectable IgG4, significantly increased IgG3, and normal IgG1. The group with IgG3 deficiency and the selected patients with the phenotype Gm(a,",g) expressed instead normal IgG4 and nearly normal IgG2 and IgG1 levels. The lack of G2m(n) together with lack of one or the other of the alternative G1m genes and corresponding G3m genes give different IgG2 levels and different IgG subclass patterns. The frequency of G1m allotypes and corresponding G3m allotypes also deviated significantly when the IgG2 deficiency and IgG3 deficiency groups were compared with each other. Most IgG subclass-deficient patients are homozygous in the Gm system and lack genetic variants in the three IgG subclasses, IgG1, IgG2, and IgG3.

Pneumococcal serum antibody concentrations during the first three years of life: a study of otitis-prone and non-otitis-prone children

One hundred and thirteen children were followed prospectively from birth until the age of 3, serum being obtained from cord blood, and at the ages of 3, 6, 12, 18, 24, 30 and 36 months. Thirteen children developed recurrent acute otitis media (rAOM), 29 remained very healthy and the remaining children formed an intermediate group. Cord serum concentrations were determined of total IgG class, of IgG1 and IgG2 subclasses, as well as of specific IgG antibodies against the pneumococcal capsular types, 3, 6A and 19F. The specific pneumococcal IgG as well as IgA and IgM antibodies were also followed in the sequential serum samples up to the age of 3 in the rAOM and healthy children. Despite total IgG class and IgG1 and IgG2 subclass concentrations being of the same magnitude in cord serum of rAOM (median: 11.15, 7.48 and 2.16 g/l for IgG, IgG1 and IgG2, respectively) as in that of healthy children (median: 10.21, 8.16 and 2.16 g/l, respectively), both in cord serum and in most serum samples drawn during the first year of life, specific IgG antibodies against types 6A and 19F, but not against type 3, were significantly lower in the rAOM group than in the healthy children. In the intermediate group, cord serum concentrations of specific IgG antibodies to type 6A were of the same magnitude as in the healthy children. The only significant difference in specific IgM and IgA antibody concentrations against types 3, 6A and 19F between the two groups was noted for type 6A antibodies at 36 months of age where rAOM children exhibited lower values. The results indicate an association between pre-existing low specific IgG antibody levels against AOM-associated pneumococcal types and the development of rAOM.

One allele [G2m(n)] of the human IgG2 locus is more productive than the other

Earlier investigators have shown that a high serum concentration of IgG2 and a high IgG2 antibody response to several polysaccharide antigens is associated with the allotype G2m(n) of the IgG2 subclass. We now show that the total IgG2 concentrations are significantly higher in G2m(n) than in G2m(-n) homozygotes (difference of means was 1.26-fold, p = 0.002). Furthermore, in G2m(n) heterozygotes, the G2m(n) allele contributed more than the G2m(-n) allele to specific IgG2 antibody responses and to the total IgG2.

IgG subclasses of pneumococcal antibodies--effect of allotype G2m(n)

Antibody responses to three pneumococcal polysaccharides (types 3, 14, and 18C) were analysed after vaccination with a 23-valent polysaccharide vaccine. Antibodies to all three polysaccharides could be detected before immunization. Clear cut IgG, IgA, and/or IgM antibody responses to the polysaccharides were seen in three-quarters of the vaccinees. IgG2 was the predominant and IgG1 the second most abundant subclass of anti-pneumococcal IgG antibodies both before and after the vaccination. The relative proportions of IgG2 and IgG1 antibodies exhibited a continuous variation from 1:0 to approximately 0:2. After vaccination, G2m(n)-positive homozygotes had about four times more IgG2 antibodies (anti-14 and anti-18C) than G2m(n)-negative vaccinees. Heterozygotes occupied an intermediate position. The same pattern was seen less clearly in type 3 antibodies after vaccination, and in all three antibodies before vaccination. The G2m(n) allotypes had no detectable effect on the levels of IgG1, IgG4, or IgM antibodies, and possibly a weak effect on IgG3 and IgA antibodies (G2m(n)-positive homozygotes responded strongly).

Immunogenicity of the Haemophilus influenzae type b capsular polysaccharide conjugate vaccine in children after systemic Haemophilus influenzae type b infections

We immunized 24 patients (mean age 15.2 +/- 9.3 months) with polyribosylribitol phosphate-diphtheria toxoid conjugate vaccine (PRP-D) 2 months after a systemic Haemophilus influenzae type b infection. Children less than 24 months of age were immunized twice. Serum was obtained for antibody to PRP before and 1 or 2 months after immunization. Three of five children greater than 24 months of age and three of six children 18 to 24 months of age developed greater than 1 microgram/ml of antibody after immunization, and geometric mean postimmunization levels were significantly greater than preimmunization levels for both groups. However, two children who failed to respond to conventional PRP vaccine did not respond as expected to one dose of PRP-D. For children 7 to 17 months of age, the geometric mean PRP antibody levels increased as follows: preimmunization, 0.05 micrograms/ml; after the first dose, 0.28 micrograms/ml (p = 0.003); and after the second dose, 3.39 micrograms/ml (p = 0.001). Of 13 children, 10 developed antibody values greater than 1.0 micrograms/ml. PRP conjugate vaccines are immunogenic in young children who have not developed protective PRP antibody levels after a systemic H. Influenzae type b infection.

Immunoglobulin genes, HLA-B8/DR3, and immune responsiveness to primary immunogen and mitogens in normal subjects

The genetic regulation of immune responsiveness by genes from two independent, highly polymorphic genetic systems, namely immunoglobulin allotypes and human leukocyte antigens (HLA), was studied in 35 healthy Caucasian volunteers. The in vivo IgG class antibody response to the primary test immunogen alpha-helix pomatia hemocyanin (HPH) was increased in subjects with the Gm1,17;..;21 haplotype compared to that of the non-Gm1,17;..;21 group. The IgM-class response tended to be higher in the former group. Levels of in vivo IgA-class-specific anti-HPH antibodies tended to be higher in the group of individuals positive for HLA-B8/DR3 than in the non-B8/DR3 group. This difference was statistically significant only in the absence of the Gm1,17;..;21 haplotype. The in vitro lymphocyte proliferative response on mitogenic stimulation with phytohemagglutinin (1 micrograms/ml) and pokeweed mitogen (10 micrograms/ml) also appeared to be associated with both systems. The presence of the Gm1,17;..;21 haplotype was associated with decreased lymphocyte reactivity, whereas the B8/DR3 phenotype was associated with high responsiveness to these mitogens. However, in the presence of the Gm1,17;..;21 haplotype subjects positive for HLA-B8/DR3 did not respond better to mitogenic stimulation than those lacking this HLA haplotype. Our results imply that the immunogenetic make-up of test persons should be taken into account in the assessment of the immune status of individuals or groups of patients.

Reimmunization of children immunized at 18 months of age with Haemophilus influenzae type b vaccine

We studied the response to reimmunization at 36 months of age with Haemophilus influenzae type b (Hib) polyribosylribitol phosphate (PRP) capsular polysaccharide vaccine. Children enrolled in the study had previously received PRP or PRP plus diphtheria and tetanus toxoids with pertussis vaccine at 18 months of age. A control group of children, who received a first dose at 36 months of age, was also studied. Ninety-five percent of children receiving a second dose of vaccine had a postimmunization anti-capsular antibody level of greater than or equal to 1 microgram/mL. In comparison, 70% of 36-month-old children who received their first dose of PRP had a postimmunization level greater than or equal to 1 microgram/mL (P = 0.09). The geometric mean titer at 37 months of age was 8.64 micrograms/mL in children who had received two doses of PRP vaccine, compared with 2.19 micrograms/mL in the group who received only one dose of PRP at 36 months of age (P = 0.04). We conclude that infants immunized at 17 to 19 months of age with PRP had an excellent immunologic response to reimmunization at 36 months of age.

Minimal role for the spleen in antibody responses of C57BR/cdj mice to pneumococcal polysaccharide antigens

The role of the spleen in antibody production and in susceptibility to pneumococcal infections remains poorly understood. Recently we showed that in A/J mice high antibody responses to polysaccharide antigens depend upon dosage, antigenic structure, interval between immunization and assay and the presence of the spleen. To investigate the possibility of alternative patterns of response, intact and splenectomized (Sx) C57BR/cdj mice were assayed for antibody responses to two structurally different pneumococcal polysaccharides, type 3 (SIII) and type 14 (SXIV). After 50 or 100 ng of SIII, intact C57BR/cdj mice produced uniformly low antibody responses that were further suppressed by splenectomy, but after 1,000 ng of SIII, C57BR/cdj mice, regardless of whether they were intact or Sx, produced antibody responses as high as those of intact A/J mice. Following SXIV, a spleen-dependent antigen, C57BR/cdj mice produced consistently lower antibody responses than A/J mice. Antibody responses to 500 or 5,000 ng of SXIV were totally obliterated in Sx C57BR/cdj mice; but unlike A/J mice, responses to 10,000 ng were similar regardless of whether C57BR/cdj mice were intact or Sx. The inability of intact C57BR/cdj mice to produce elevated responses to SIII or SXIV suggests that C57BR/cdj mice may lack the subset of spleen cells necessary for a vigorous response to these antigens. The data suggest that these mice could provide useful animal models for studying host variability in antibody responses to pneumococcal polysaccharides.

Prospects for overcoming maturational and genetic barriers to the human antibody response to the capsular polysaccharide of Haemophilus influenzae type b

The isolated capsular polysaccharide induces antibody protective against invasive infections by H. influenzae b. Maturation of responsiveness is slow such that infants are not protected. Several protein-coupled versions of the antigen are being tested for immunogenicity in early infancy. The relation of structure to immunogenicity is not completely defined, but all induce a booster-type antibody response with protective potential. Primary vaccination in infancy appears to mimic natural priming, activating clones of B lymphocytes that can later be restimulated by uncoupled polysaccharide. Prospects appear good for immunizing normal infants and also children with immunoregulatory defects predisposing to infection.

Immunoregulatory role of the spleen in antibody responses to pneumococcal polysaccharide antigens

Antibody responses to two structurally different pneumococcal polysaccharides, type 3 (SIII) and type 14 (SXIV), were examined in intact and splenectomized (Sx) A/J mice to determine whether the role of the spleen in immune responses to these antigens varies with respect to the dosage, the antigenic structure, or the interval between immunization and assay. Antibody responses to SIII and SXIV, measured over a 4-week period by radioimmunoassay, differed in antigenic load requirements, kinetics, and extent of dependence upon the spleen. Intact mice given 50 or 100 ng of SIII produced peak antibody responses on day 5, which tapered off by days 14 and 21. Intact mice given SXIV required doses 100 times greater than those of SIII to stimulate high levels of antibody response; antibody responses increased on day 5 and remained elevated through day 28. In Sx mice given 50 or 100 ng of SIII, the peak antibody response on day 5 was obliterated, but extrasplenic sources produced low levels of antibody which peaked by day 14. In Sx mice given SXIV, all anti-SXIV responses were abrogated regardless of the dose or day of assay. Differences between the anti-SIII and anti-SXIV responses in dependence upon the spleen were probably due to structural differences between the two antigens and to the localization of each to different sites in the reticuloendothelial system. These results attest to the importance of the spleen in antibacterial resistance. They show that, even in the presence of extrasplenic antibody synthesis, the spleen is required for early antibody production, the timing of which is critical for the effective clearance of bacteria.

C2 deficiency, moderately low IgG2 concentrations and lack of the G2m(23) allotype marker in a child with repeated bacterial infections

C2 deficiency was demonstrated in an 11-year-old boy with a past history of recurrent purulent otitis media, pneumonia, H. influenzae meningitis and S. pneumoniae septicaemia. The major histocompatibility complex haplotypes present, A10, B18, DR2, BF*S, C2*QO, C4*A4, C4*B2 and A28, B18, DR2, BF*S, C2*Q0, C4*A4, C4*B2, were in accord with previous observations in C2 deficiency. The concentrations of C1q, C5, factor B and factor D were in the low normal range and the hemolytic activity of the alternative pathway was slightly decreased. In addition, the patient showed moderately low IgG2 concentrations and lacked the IgG2 subclass marker G2m(23). The findings indicate that the patient's susceptibility to bacterial infections may be due to C2 deficiency in combination with the presence of an IgG allotype associated with impaired antibody responses to carbohydrate antigens.

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.

Direct evidence that decreased serum opsonization of Streptococcus pneumoniae via the alternative complement pathway in sickle cell disease is related to antibody deficiency

Two approaches were used to demonstrate that reduction in serum opsonization of Streptococcus pneumoniae via the alternative complement pathway in children with sickle cell disease is related to a deficiency of antibodies to pneumococcal capsular polysaccharide. First, opsonization of S. pneumoniae mediated by the alternative pathway in patients' sera was restored to normal by addition of the purified IgG or IgM fraction of goat antiserum to capsular polysaccharide of the homologous serotype. Secondly, IgG antibody titers to capsular polysaccharide in patients' sera correlated significantly with alternative pathway-mediated opsonization; the correlation between titers of IgM anticapsular antibodies and opsonization approached statistical significance. The sum of the IgG and IgM anticapsular antibody titers correlated most significantly with opsonization. Our results suggest that reduction in alternative pathway-mediated opsonization in sera from children with sickle cell disease is related to low levels of both IgG and IgM anticapsular antibodies.

Hemophilus influenzae type B disease in children vaccinated with type B polysaccharide vaccine

We studied 55 cases of invasive Hemophilus influenzae type b disease occurring in children at least three weeks after vaccination with type b polysaccharide vaccine. Their mean age at the time of immunization was 27.8 months (range, 18 to 47). Meningitis developed in 39 patients, of whom 3 died and 6 had neurologic sequelae. We investigated certain host factors that may have contributed to the failure of the vaccine. The geometric mean concentration of antibody to type b polysaccharide in convalescent-phase serum from 31 of the vaccinated patients who had hemophilus disease was significantly lower than that in serum from 25 patients of similar age with the disease who had never been vaccinated (0.59 vs. 3.46 micrograms per milliliter, P less than 0.001). However, only 3 of 46 patients in whom the vaccine failed and who were tested for hypogammaglobulinemia had this finding, and none of 33 children tested for IgG2 had low serum concentrations of this immunoglobulin subclass, which is thought to be important in the immune response to polysaccharide antigens. In addition, all but 1 of the 46 patients in whom the vaccine failed and who were tested for IgG antibody to tetanus toxoid protein, a thymic-dependent antigen, had normal values, and 19 of 20 tested for hemolytic complement activity had normal levels. In white children, the presence of the Gm immunoglobulin phenotype (1,2,3, 17; ;5,13,21) was associated with a sevenfold increase in the relative risk of vaccine failure (P less than 0.003). We conclude that vaccine failure may be related in part to genetic factors, and that most vaccinated children in whom Hemophilus influenzae disease develops have deficient antibody responses to the type b polysaccharide despite normal serum concentrations of immunoglobulin and normal antibody responses to tetanus toxoid.

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.