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Polymorphism in the IGKV2-29 gene was shown to decrease the recombination frequency in B cells and to be important for immune responses to Haemophilus influenzae type b polysaccharide. By using the combination of PCR and restriction enzyme mapping, the distribution of IGKV2D-29 and IGKV2-29 gene alleles was estimated in two geographically and ethnically different groups. We found that V2D-29*01 homozygous individuals were most common in Swedish Caucasians (82%), but less common in the Chinese population of Hong Kong (28%). The homozygous V2D-29*02 genotype was found in 19% Chinese, but only in one Caucasian (1%). The frequency of the heterozygous V2D-29*01/V2D-29*02 genotype was also higher in the Chinese population (46%) compared with the Caucasians (7%). V2-29*01 homozygosity was more frequent among Caucasians (85%) than among Chinese (19%). In contrast, homozygous V2-29*02 individuals were over-represented in the Chinese population (18%), whereas only one was found among Caucasians (1%). Heterozygous V2-29*01/V2-29*02 individuals were also more common in the Chinese (63%) than the Caucasian (15%) population. Most Caucasians had the combination of V2D-29*01/V2D-29*01+V2-29*01/V2-29*01 (74%), while the most common genotype for Chinese was V2D-29*01/V2D-29*02+ V2-29*01/V2-29*02 (41%). Analysis of the association of V2D-29*02 and V2-29*02 alleles demonstrated a high degree of linkage, as for V2D-29*01 with V2-29*01. These data show a significant difference in the distribution of IGKV2D-29 and IGKV2-29 alleles among Swedish Caucasians and Hong Kong Chinese. This may help to explain differences in the occurrence of H. influenzae type b infection in the two populations. Evaluated methods for IGKV2D-29 and IGKV2-29 allele detection can be used for the screening allele polymorphisms in other particular patient groups.

A 31-year-old woman without any underlying disease contracted severe invasive Haemophilus influenzae type b (Hib) infection but developed no antibodies to the Hib capsular polysaccharide. Serum immunoglobulin levels were normal, but she had an isolated deficiency of antibody to Hib. Subsequently, immunization with a tetanus toxoid-conjugated Hib vaccine induced only a minimal response. However, she had a protective level of antibody (> 1 microgram/mL) after the fifth vaccination.

Background: Asthma is an independent risk factor for invasive pneumococcal disease; however, the immune response of adult asthma patients to pneumococcal vaccination is unknown. We explore the serologic response of patients with moderate to severe asthma to the 23-valent pneumococcal polysaccharide vaccine (PPSV23). Methods: Seventeen moderate to severe adult asthma patients that had not been vaccinated against pneumococcus over the 5 previous years were prospectively recruited from a tertiary care asthma clinic. Serum was analyzed for the presence of antibodies to five capsular polysaccharide (CP) antigens (6B, 9V, 19A, 19F, 23F) before and 4 weeks after PPSV23 vaccination. Results: There was a wide variability in baseline anti-CP antibody concentrations. Other than for serotype 19A, our patients frequently have baseline anti-CP antibody concentrations below 1 µg/mL (35% for serotype 19F, 41% for serotypes 9V and 23F, and 59% for serotype 6B). All post-vaccination geometric mean antibody concentrations were significantly higher than baseline. In the 31 tests where the baseline antibody concentration was <1 µg/mL, 77.4% had at least a twofold increase post-vaccination. Despite this, a large proportion of post-vaccination anti-CP antibody concentrations remained <1 µg/mL (51.6% of tests). Nine patients had at least one anti-CP antibody concentration <1 µg/mL post-vaccination. There was no difference between these patients and the remaining eight patients in demographic or clinical variables. Conclusions: Patients with moderate to severe asthma have variable baseline and low post-vaccination antibody concentrations to common CP antigens included in the PPSV23 vaccine. The clinical relevance of these observations remains to be determined since the threshold concentration in adults required for clinical protection from invasive pneumococcal disease is uncertain. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the concentrations of serum antibodies against Haemophilus influenzae type b in preschool children in relation to the distribution of idiotypic antibodies 1 and 2 (Id-1 and Id-2) and the exposure to breastfeeding in infancy. Sera were obtained from 74 control children recruited in an earlier case-control study before the introduction of general Hib vaccination. Duration of breastfeeding was monitored, and prevalence of noninvasive infections was registered. Concentrations of IgG1 and IgG2 anti-Hib, as well as of total Id-1 and Id-2, were determined in ELISA. The expression of Id-1 antibodies increased with age in contrast to the Id-2 antibodies that were found only in children up to 24 months of age. Expression of Id-1 antibodies was positively correlated with higher anti-Hib levels of both the IgG1 and IgG2 isotype. Children expressing Id-2 antibodies showed higher IgG2 anti-Hib concentrations than those who did not have Id-2 ( P = 0.001). The concentrations of neither Id-1 nor Id-2 antibodies were related to the duration of breastfeeding. Duration of breastfeeding was related to increased anti-Hib IgG2 in healthy children above 18 months of age. These study shows that the expression of idiotype-1 and idiotype-2 antibodies was associated with higher IgG2 anti-Hib concentration and that breastfeeding could enhance the anti-Hib IgG2 production in children. [ABSTRACT FROM AUTHOR]

The Chinese population in Hong Kong has a low incidence of invasive Haemophilus influenzae b (Hib) disease, as well as carriage of the microorganism. Likely stimuli for the natural antibodies to Hib, which might protect against Hib infection, are cross-reactive antigens of bacteria like Escherichia coli K100. Our aim was to determine the isotype and idiotype distribution and cross-reactivity of natural antibodies against Hib capsular polysaccharide (CP) in healthy Hong Kong Chinese. Titration of 20 sera by ELISA showed IgG antibodies reading with Hib CP in all individuals. The antibodies were mainly IgG2, and their avidity index ranged widely. Isoelectric focusing (IEF) combined with immunoblotting showed patterns of IgG2 antibody clones against the CP of Hib and E. coli K.100 which were similar in 10 cases. Absorption with Hib CP only eliminated some bunds in two sera. Absorption with KHK) CP did not remove any anti-Hib CP bands. In three sera additional clones of antibodies reacting to K.100 CP only, disappeared after absorption with this CP. Spectrotypic analyses of IgG antibodies reacting with anti-Hib idiotype I (ld-1) revealed stronger IEF patterns with bands in differing locations compared with anti-Hib CP antibodies. The strong reactivity of serum IgG, IgA and IgM antibodies with monoclonal anti-Hib ld-1 was confirmed by ELISA. This reactivity was not abolished after absorption of the sera with either Hib CP. or K 100 CP. The data indicate a high prevalence of Id-l among Hong Kong Chinese. However, only one individual had ld-1 antibodies specific for Hib CP. judging from absorption experiments. Others had much lower activity of ld-1 anti-Hib CP antibodies compared with the total IgG Id-1. suggesting that Hung Kong subjects have Id-1-positive antibodies in their serum which are not specific for Hib CP. This is consistent with the nature of Id-1, which is a marker of A2VL region usage rather than a marker of a Hib CP paratope. We suggest that natural antibodies reacting with Hib CP in healthy Hong Kong Chinese are the product of exposure to some cross-reactive antigen(s), different from both Hib and E. coli K100 CP. [ABSTRACT FROM AUTHOR]

A modified fast micro method for spectrotypic/clonotypic analysis of human IgG1–4 antibodies against bacterial virulence antigens of polysaccharide or protein nature is described. Serum samples of as small volumes as 0.5 μl were isoelectrically focused in micro agarose gels made in plexiglass matrices and blotted using immunoaffinity-mediated capillary blotting onto nitrocellulose membranes previously coated with antigen. The bands of the antigen-specific antibodies were identified with respect to isotypes, light chain types, allotypes or idiotypes by incubating the nitrocellulose membranes with mouse monoclonal anti-human IgG subclass antisera and then with alkaline phosphatase-conjugated rabbit anti-mouse immunoglobulins. The method was applied for characterization of human monoclonals against tetanus toxoid (TT) and for the analysis of variable patterns of clonotypes in IgG subclass-deficient patients. The usefulness of the technique was also demonstrated by comparing the variable specificity and reactivity of different commercial monoclonals against human IgG subclasses. This method is fast, specific, sensitive, uses little material, is simple and reproducible. [ABSTRACT FROM AUTHOR]

Abstract: Prevalence of non-typeable Haemophilus influenzae (NTHi) in the etiology of invasive infections in immunocompromised individuals is increasing. Serum IgG antibody levels to H. influenzae protein D (PD) were significantly lower in adults suffering from chronic conditions causing secondary immunodeficiency (COPD, cancer, chronic renal failure, and diabetes) compared to age-matched healthy controls. A lack of naturally acquired antibody against this highly conserved antigen may contribute to an increased susceptibility to invasive NTHi disease. As COPD patients frequently infected with NTHi during disease exacerbations were unable to develop antibody response to PD, such defect could potentially contribute to the pathogenesis. Considering that pediatric PD-containing vaccines show protective effect against NTHi-caused otitis media, our data suggest the possibility of improving the defense against NTHi in COPD patients using immunization against PD. Although more research on the role of anti-PD antibody in protection against invasive NTHi disease is warranted, development of adult formulations of PD-based vaccines may be advantageous for prevention of severe infections in immunocompromised individuals. [Copyright &y& Elsevier]