IgA is the predominant immunoglobulin isotype in mucosal tissues and external secretions, playing important roles both in defense against pathogens and in maintenance of commensal microbiota. Considering the complexity of its interactions with the surrounding environment, IgA is a likely target for diversifying or positive selection. To investigate this possibility, the action of natural select...

We have previously shown that human B lymphocytes cultured in the CD40 system, composed of an anti-CD40 mAb presented by a CD32-transfected fibroblastic cell line, proliferate but do not secrete antibodies. However, the addition of particles of Staphylococcus aureus Cowan (SAC) induces B cell differentiation even in the absence of exogeneous cytokines (CD40/SAC system). Additionally, B lymphocy...

The temporal association of tonsillitis and hematuria or proteinuria in IgA nephropathy suggests that there might be a link between the physiological properties of the secondary lymphoid organ that tonsils represent and the mesangial deposition of IgA characteristic of this nephropathy. A number of clinical and ex-vivo data support this hypothesis. One of the earliest was the demonstration of t...

BACKGROUND The clinical utility of testing for antiphospholipid antibodies (aPL) of IgA isotype remains controversial. METHODOLOGY/PRINCIPAL FINDINGS To address this issue, we reasoned that if IgA aPL contribute to the clinical manifestations of the antiphospholipid syndrome, then an association with thromboembolic events should manifest in patients whose only aPL is of IgA isotype. We perfor...

The finding in primary IgA nephropathy of increased levels of IgA to food antigens and particularly to gliadin prompted the hypothesis that a subgroup of these patients may have latent coeliac disease. The observation that gliadin may experimentally induce IgA mesangial deposits supported this hypothesis. We evaluated specific immunological markers of coeliac disease (antiendomysium antibodies)...

We have previously shown that human B lymphocytes cultured in the CD40 system, composed of an anti-CD40 mAb presented by a CD32-transfected fibroblastic cell line, proliferate but do not secrete antibodies. However, the addition of particles of Staphylococcus aureus Cowan (SAC) induces B cell differentiation even in the absence of exogeneous cytokines (CD40/SAC system). Additionally, B lymphocy...

1. Five patients with congenital or acquired agammaglobulinemia, lacking detectable IgA in serum or saliva, were transfused with 1 to 2 liters of normal plasma. In 2 of these patients IgA was demonstrated in parotid saliva collected after transfusion, but in none of the 5 was salivary IgG or IgM found. This observation indicates the selective transport of IgA into saliva. 2. The observation by ...

The detection of molecular weights of IgA-circulating immune complexes (CIC) in sera is described. Measurement of IgA-, IgG- and IgM-CIC in sera was also performed. Serum samples were obtained from nine patients with IgA nephropathy, nine patients with chronic proliferative glomerulonephritis without IgA deposits (PGN) and 19 healthy adults. Serum samples of these patients were subjected to hig...

This study investigated changes in resting-state functional connectivity (rsFC) of posterior cingulate cortex (PCC) in smokers and nonsmokers with Internet gaming addiction (IGA). Twenty-nine smokers with IGA, 22 nonsmokers with IGA, and 30 healthy controls (HC group) underwent a resting-state fMRI scan. PCC connectivity was determined in all subjects by investigating synchronized low-frequency...

A T cell receptor transgenic mouse line reactive to a microbiota flagellin, CBir1, was used to define mechanisms of host microbiota homeostasis. Intestinal IgA, but not serum IgA, was found to block mucosal flagellin uptake and systemic T cell activation in mice. Depletion of CD4(+)CD25(+) Tregs decreased IgA(+) B cells, total IgA, and CBir1-specific IgA in gut within days. Repletion of T cell-...