Quantitation of Ig classes and IgG subclasses in sera of patients with a variety of immunoglobulin deficiencies and their relatives

High immune responsiveness in a family with multiple paraproteinaemia and autoimmune thyroid disease

Immune responsiveness was investigated in a family comprising 12 first- and second-degree relatives, one of whom had kappa-myelomatosis, one IgA-lambda paraproteinaemia, two Graves' disease and a further two thyroid antibodies without disease. Relatives by marriage served as controls. Parameters of immune capacity studied were the humoral and cellular immune response to haemocyanin of Helix pomatia (HPH), dinitrochlorobenzene (DNCB) skin reactivity and in vitro lymphocyte proliferation capacity to phytohaemagglutinin (PHA). Mean antibody titres to HPH were higher in the family than in the control group in all main Ig classes and IgG subclasses after primary and secondary immunization, and the difference was statistically significant for IgG, IgG2 and IgG4 titres. This could not have been predicted from the (normal) serum Ig levels in this family. In vitro lymphocyte proliferation capacity to HPH after primary and secondary immunization was also significantly increased. DNCB skin reactivity also tended to be high in the family, whereas PHA-induced lymphocyte proliferation was normal. These findings support the idea that myelomatosis clusters in families with immune dysregulation.

Immediate hypersensitivity in adults with IgG deficiency and recurrent respiratory infections

BACKGROUND

Little is known about the prevalence of atopy in adults with recurrent respiratory infections and IgG deficiency.

OBJECTIVE AND METHODS

To elucidate this aspect, we skin-tested 95 consecutive adults with respiratory infections, subnormal levels of IgG subclasses or common variable immunodeficiency and usually poor response to vaccination. In 50 subjects we also measured total IgE.

RESULTS

We found 67 subjects with IgG subclass deficiency, 21 subjects with mild (partial) and 5 with usual common variable immunodeficiency, and 2 subjects with functional IgG deficiency. Atopy was encountered in 42/95 subjects, 33/44 (75%) with asthma, 7/19 (38%) with isolated rhinosinusitis, 1/27 (4%) with chronic obstructive lung disease, and 1/5 (20%) with both the latter disease and asthma, respectively. Atopy was preferentially clustered in subjects with asthma (P < .05) who were less than 40 years of age (P < .05) and nonsmoking. Atopy was not affected by the type of IgG deficiency, unless it was usual common variable immunodeficiency, in which case the skin tests tended to be negative (4/5). Total IgE was within normal range but less elevated than usually seen in asthma or chronic obstructive lung disease. Total IgE was independent of the type of IgG deficiency, except for usual common variable immunodeficiency in which it remained < 10 IU/mL.

CONCLUSIONS

In adults with symptomatic IgG deficiency, the prevalence of immediate hypersensitivity and its modulation by age and smoking are similar to the referred, non-IgG deficient population; however, total IgE may be lower in the former than in the latter. In common variable immunodeficiency, consistent with the literature data, both the prevalence of atopy and serum total IgE are decreased.

IgG subclass potential of surface IgM-negative and surface IgM-positive human peripheral blood B cells

To examine the IgG subclass potential of B cells at various stages of maturation, human peripheral blood B cells were separated into surface IgM-positive (sIgM+) and surface IgM-negative (sIgM-) cells by panning techniques and cultured with pokeweed mitogen, LPS, or Epstein-Barr virus. At the end of 7 days, cells were harvested, counted, spun onto slides, fixed, and stained with subclass-specific monoclonal antibodies. In all experiments with all mitogens, there was an enrichment of IgG2 plasma cells in sIgM+ cultures compared to the sIgM- cultures (P less than 0.0001). In the Epstein-Barr virus-stimulated cultures there was also a statistically significant enrichment for IgG3 in the sIgM+ cultures (P less than 0.01). In contrast, sIgM- cultures were always enriched for IgG1 plasma cells (P less than 0.0001). In the pokeweed mitogen-stimulated cultures, the sIgM- cultures also contained a higher proportion of IgG4 plasma cells than did the sIgM+ cultures (P less than 0.01). These results demonstrate that the IgG subclass potential of immature, surface IgM-positive precursors of IgG plasma cells differs from that of more mature surface IgM-negative precursors.

Selective IgA deficiency: analysis of Ig production in vitro

The cellular basis of the pathogenesis of selective IgA deficiency (SIgAD) was investigated by examining surface immunoglobulin (SmIg) and in vitro pokeweed mitogen (PWM)-stimulated immunoglobulin (Ig) synthesis and by assaying in combination the counterpart lymphocytes from individuals with SIgAD and healthy donors. Peripheral blood lymphocytes (PBL) from 14 individuals with SIgAD synthesized normal amounts of IgG and IgM but did not synthesize normal amounts of IgA. Functional defects of lymphocytes for IgA synthesis were classified into four types: (i) B-lymphocyte dysfunction, (ii) increased function of suppressor T lymphocytes (Ts), (iii) decreased function of helper T lymphocytes (Th), and (iv) B-lymphocyte dysfunction and increased Ts function. The cells bearing SmIgG, SmIgM, and SmIgD were demonstrated at normal percentage ratios in all cases by immunofluorescent staining. The cells bearing SmIgA were at normal percentage ratios in the cases of T-lymphocyte dysfunction, while in the cases of B-lymphocyte defect SmIgA-bearing cells were reduced.

Lack of IgG in a healthy adult: a rare case of dysgammaglobulinemia with undetectable serum IgG, IgA2, and IgE

No IgG of any subclass could be detected in the serum of a normal healthy male adult (E.E.) who had no recent history of repeated infections. Markedly increased concentrations of both IgM and IgA were present although no IgA2 nor IgE could be demonstrated. No anti-immunoglobulin antibodies were present in the serum; when used as supplement in in vitro cultures, the serum supported differentiation of IgG-producing cells to an equal extent as that of normal serum. No cells with surface or intracellular IgG were found in the peripheral blood although low numbers of IgG-secreting cells could be induced in vitro after mitogen stimulation. No increase in suppressor cell activity was found in cocultivation experiments. T-Cell-enriched populations from E.E. were poor inducers of immunoglobulin synthesis in allogeneic B cells, and B-cell-enriched populations from E.E. could not be triggered to synthesize IgG with the aid of allogeneic T cells. Thus, it seems that lack of IgG does not necessarily lead to a highly increased susceptibility to bacterial infections.

Serum levels of IgA1 and IgA2 in children and in patients with IgA deficiency

Serum levels of IgA1 and IgA2 were measured by solid phase radioimmunoassay in samples from 110 children between 3 months and 10 years of age. Both IgA1 and IgA2 were detectable in all samples, and both IgA1 and IgA2 increased with increasing age. The percent of total serum IgA that was IgA2 did not change with age and was the same in samples from children (15.05 +/- 10.2%) as in samples from adults (15.86 +/- 7.98%). The proportion of serum IgA that was IgA2 was much less variable within sibships than within the group at large (P less than 0.005). In the 16 patients with IgA deficiency, the proportion of serum IgA that was IgA1 or IgA2 was highly variable. IgA2 constituted more than 50% of the IgA in 5 patients and less than 7% of the IgA in an additional 5 patients. These findings suggest that regulation of serum concentrations of IgA1 and IgA2 is complex and influenced by genetic factors and probably other unidentified factors.

Gene deletion and gene duplication within the cluster of human heavy-chain genes. Selective absence of IgG sub-classes

Individuals with selective absence of IgG1 and IgG2 were discovered by testing for allotypes and isotypes of the respective sub-classes. These individuals were homozygous for sub-class deleted Gm-Am haplotypes, as shown by allotype studies in two families (Gm--;..;g;A2m1/Gm--;n;b;A2m1 and Gm--;n;b;A2m1/Gm--;..;b;A2m1) and by a population study of New Guineans (Gm fa;--;b;A2m2). The individuals with IgG1 sub-class deficiency showed elevation of IgG2, IgG4 and in particular of IgG3. Gene deletion can result from unequal crossing over which renders a complementary chromosome with a duplication of a sub-class gene. In one family, duplication of gamma 3 genes was observed to have happened in one of a twin pair. Quanitation of sub-classes in families with gamma 1- and with gamma 3-duplicated haplotypes did not show increased levels of the gene involved.

Discontinuous genes and DNA sequence transposition: a model for immunoglobulin chain synthesis

An attempt is made to account for immunoglobulin chain synthesis in terms of genetic events involving IS or controlling elements analogous to those found in bacteria, maize and drosophila. Transposition of variable and constant genes and normal immunoglobulin chain synthesis as well as qualitative and quantitative abnormalities might be explained by such regulatory elements. Intrachromosomal transpositions over short distances would be expressed as apparent hypermutability or redundancy of the variable DNA segment. The constant gene might comprise four sequences coding for the three homology domains and the hinge, separated by intervening sequences. A strong preference for short-range transposition on the same chromosome and immobilization of the controlling element in the end might account for allelic exclusion.