Human T-helper clones induce IgG production in a subclass-specific fashion.

The mechanisms governing the induction of IgG subclasses by T-helper cells in humans were investigated. As preliminary bulk-culture experiments had indicated that a direct B cell contact with viable T cells was an essential requirement for optimal IgG subclass production, 256 CD4+ human T cell clones were preactivated with PHA and cultured in direct contact with autologous B cells. These clones induced IgG production in a strikingly subclass-specific fashion. Moreover, the distribution of subclass-specific helper clones was very similar to the IgG subclass profile observed in serum and peripheral lymphoid tissue plasma cells (IgG1 approximately 60%, IgG2 approximately 30%, IgG3 approximately 5-10%, IgG4 less than or equal to 5%) and unlike that observed in resting B cells (which is IgG1 approximately 40% and IgG2 approximately 50%). It would, therefore, seem that a predominance of T cells capable of delivering IgG1-specific, as opposed to IgG2-specific, help is an essential factor for the preferential induction of IgG1 antibodies during B cell proliferation and differentiation. There was no relationship between IL2, IL4, IL6, and IFN-gamma secreted by the T-helper clones and their IgG subclass induction patterns. In addition, only a few supernatants were able to reproduce the helper effects of the clones themselves. Therefore, direct contact of B cells with helper clones is crucial for IgG-subclass production in humans.

IgG subclass deficiency and sinopulmonary bacterial infections in patients with alcoholic liver disease.

Abnormalities in IgG subclass distribution were sought in serum samples and bronchoalveolar lavage fluid from 15 patients with alcoholic liver disease to explain their increased susceptibility to bacterial respiratory infections. Serum IgG4 deficiency alone or in association with low IgG2 levels was revealed in approximately 30% of patients with alcoholic liver disease. This fact prompted us to further investigate the immunoglobulin concentrations in broncho-alveolar lavage fluid, paying special attention to the distribution of IgA and IgG subclasses. IgA levels were found to be normal or slightly elevated. However, there were substantial defects in total IgG and IgG1 concentrations, often associated with reduced IgG2 and IgG4 levels, in approximately 70% of patients with alcoholic liver disease, which proved to be closely correlated with the number and type (pneumonia) of bacterial respiratory infections. A prospective study of intravenous immunoglobulin substitutive therapy involving two patients with recurrent pneumonia and very low serum IgG2 values demonstrated a reduction in the number of respiratory infectious episodes as well as an increase in both serum and, to a lesser extent, bronchoalveolar lavage fluid IgG1 and IgG2 levels. We identified immune defects that may represent an important pathogenetic mechanism that, when considered together with the alcohol-related suppression of alveolar macrophage and ciliary functions and the inhibition of leukocyte migration into the lungs, should help clarify the complex relationships between alcohol and immune defense.

[Immunotherapy in allergic diseases. Evaluation of short-term efficacy of aluminum hydroxide-absorbed slow-release preparations]. / L'immunoterapia nelle malattie allergiche. Valutazione dell'efficacia a breve termine di preparati ritardo assorbiti su idrossido di alluminio.

Clinical and immunological changes after immunotherapy (ITS) for respiratory allergy were evaluated in 29 subjects during a one year follow up period. No adverse effects were noted with alum-absorbed allergen extracts. However, only patients receiving ITS for grass pollens demonstrated clinical improvement and blocking IgG increase as compared with those with multiple allergen sensitivity.

[The determination of specific IgE in allergy diagnosis. The clinical significance of specific IgE in drug allergies]. / Il dosaggio delle IgE-specifiche nella diagnostica allergica. Significato clinico delle IgE-specifiche nelle allergie a farmaci.

IgE-mediated allergic reactions to drugs may be diagnosed on the basis of anamnestic criteria, clinico-pathological manifestations as well as by the measurement of allergen-specific IgE. The concordance of these diagnostic procedures was investigated in 50 patients with a history of sensitivity to penicillin (12), sulphamethoxazole (9) or both (14), aspirin (2) and pyrazolones (13). All subjects displayed chronic urticaria/angioedema syndrome. Optimal concordance values were observed for penicillin and sulphamethoxazole, while no specific IgE were detected in the ASA-sensitive group. False positive results were noted in pyrazolone-sensitive patients with high total IgE levels. Based on these results, serological methods that detect drug-specific IgE may be carefully used as complementary diagnostic procedure only in those patients in whom an adverse reaction to antibiotics is suspected.

[Determination of circulating immune complexes and complement activation in patients with urticaria-angioedema syndrome]. / Rilevazione di immunocomplessi circolanti ed attivazione del complemento in pazienti con sindrome orticaria-angioedema.

In the present study, we examined 102 patients with chronic urticaria and angioedema. The incidence of immune complexes (CIC)-mediated chronic urticaria with complement activation (C3b+) was 11.7% (12/102 patients). The 12 patients with CIC and C3b was divided in three diagnostic groups: with drug adverse reactions; with systemic disorders; without apparent associated pathologies. On the basis of data obtained it is remarkable the necessity of a careful etiologic diagnosis in presence of CIC mediated-chronic urticaria particularly when it is associated with arthralgies and/or elevated erythrocyte sedimentation rate (ESR) because of a likely presence of a serious systemic pathology.