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.

Diphtheria antitoxin levels in US blood and plasma donors

Plasma samples from 500 blood donors were titrated for diphtheria antitoxin (DAT) by the toxin neutralization (TN) test. Only 1.6% of donors had <0.01 IU/mL DAT, the minimum protective level against diphtheria; 15% had levels between 0.01 and <0.1 IU/mL, indicating basic protection, and 83.4% had levels > or =0.1 IU, indicating full protection. Three hundred fifty samples were studied by ELISA for diphtheria toxoid IgG antibodies to assess the utility of the assay as a quick, convenient method for evaluating diphtheria immunity. Although the correlation between TN and ELISA titers for the 350 samples was high (r = .80), there was no correlation (r = .07) for samples with antitoxin titers <0.1 IU/mL, the level of special interest for serosurveys for protection. Titration of 62 immune globulin samples (prepared from 1957 to 1994) showed that DAT levels in Massachusetts blood donors increased concurrently with increased use of tetanus-diphtheria vaccine in the state.

Evaluating the effects between metal mixtures and serum vaccine antibody concentrations in children: a prospective birth cohort study

BACKGROUND

Many populations are exposed to arsenic, lead, and manganese. These metals influence immune function. We evaluated the association between exposure to single and multiple metals, including arsenic, lead, and manganese, to humoral immunity as measured by antibody concentrations to diphtheria and tetanus toxoid among vaccinated Bangladeshi children. Additionally, we examined if this association was potentially mediated by nutritional status.

METHODS

Antibody concentrations to diphtheria and tetanus were measured in children's serum at age 5 (n = 502). Household drinking water was sampled to quantify arsenic (W-As) and manganese (W-Mn), whereas lead was measured in blood (B-Pb). Exposure samples were taken during pregnancy, toddlerhood, and early childhood. Multiple linear regression models (MLRs) with single or combined metal predictors were used to determine the association with antibody outcomes. MLR results were transformed to units of percent change in outcome per doubling of exposure to improve interpretability. Structural equation models (SEMs) were used to further assess exposure to metal mixtures. SEMs regressed a latent exposure variable (Metals), informed by all measured metal variables (W-As, W-Mn, and B-Pb), on a latent outcome variable (Antibody), informed by measured antibody variables (diphtheria and tetanus). Weight-for-age z-score (WFA) at age 5 was evaluated as a mediator.

RESULTS

Diphtheria antibody was negatively associated with W-As during pregnancy in MLR, but associations were attenuated after adjusting for W-Mn and B-Pb (- 2.9% change in diphtheria antibody per doubling in W-As, 95% confidence interval [CI]: - 7%, 1.5%). Conversely, pregnancy levels of B-Pb were positively associated with tetanus antibody, even after adjusting for W-As and W-Mn (13.3%, 95% CI: 1.7%, 26.3%). Overall, null associations were observed between W-Mn and antibody outcomes. Analysis by SEMs showed that the latent Metals mixture was significantly associated with the latent Antibody outcome (β = - 0.16, 95% CI: - 0.26, - 0.05), but the Metals variable was characterized by positive and negative loadings of W-As and B-Pb, respectively. Sex-stratified MLR and SEM analyses showed W-As and B-Pb associations were exclusive to females. Mediation by WFA was null, indicating Metals only had direct effects on Antibody.

CONCLUSIONS

We observed significant modulation of vaccine antibody concentrations among children with pregnancy and early life exposures to drinking water arsenic and blood lead. We found distinct differences by child sex, as only females were susceptible to metal-related modulations in antibody levels. Weight-for-age, a nutritional status proxy, did not mediate the association between the metal mixture and vaccine antibody.

Diphtheria-neutralizing antibody levels in healthy adults from Rio de Janeiro, Brazil

In Brazil, until 2004, the immunization policy against diphtheria involved childhood vaccination with no official routine booster dose administered after 15 years of age. This study assessed functional antibody levels against diphtheria among blood donors. A total of 140 blood samples were collected, and diphtheria antitoxin levels were evaluated by Vero cell neutralization test. The mean age of the population was 34 years old (range: 18-61 years); 37.8% females and 62.2% males. Overall, 30.7% (95%, CI: 23.4-38.7) individuals presented neutralizing antitoxin antibody titers < 0.01 IU/ml; 42.1% (95%, CI: 34.1-50.4) showed values between 0.01-0.09 IU/ml and, 27.1% (95%, CI: 20.2-34.9) had (3) 0.1 IU/ml. In the subgroup of individuals with history of diphtheria immunization during childhood (85%), a number of 28.5% showed unprotective levels of circulating neutralizing antibody (< 0.01 IU/ml). Despite the continuous progress of immunization programs directed to Brazilian population, currently healthy adults remain susceptible to diphtheria.

[Hemosorption in serotherapy (serosorption) in experimental acute diphtheric toxemia with the use of affinity sorbents]

In modeling acute diphtheric toxemia in guinea pigs, the authors propose to perform hemosorption using selective sorbents under continuous introduction of antitoxic immune sera into extracorporeal contour in front of sorption column. Combination of hemosorption with serotherapy in the same time interval may be denoted as serosorption. As specific sorbents, affine preparations imasorb A-700 and Imasorb G-700 were used. They selectively eliminate from the blood flow CIC produced by diphtheric toxin (anatoxin) and antitoxic rabbit and horse antibodies. Changes in the titers of the diphtheric toxin (anatoxin) and CIC in blood evidence for efficiency of selective sorbents were confirmed by immunohistochemical analysis of the preparations' granules after hemoperfusion.