Monoclonal antibodies were used to examine the immunoglobulin isotypes expressed by B lymphocyte precursors of IgM, IgG, IgA, and IgA2 plasma cells. Plasma-cell differentiation was induced by the addition of pokeweed mitogen to cultures of blood mononuclear cells. Anti-mu, -gamma, -alpha, and -alpha 1 antibodies were used in some experiments to inhibit differentiation of B lymphocytes bearing t...

Neisseria meningitidis secretes a protease that specifically cleaves the hinge region of immunoglobulin A1 (IgA1), releasing the effector (Fc) domain of IgA1 from the antigen binding (Fab) determinants. Theoretically, the remaining Fab fragments can block pathogen receptors or toxins and still provide protection. Here, we describe binding of V-gene-matched human IgA1 and IgA2 to PorA of strain ...

A series of 20 bone marrow trephines biopsy and necropsy specimens were stained for IgA1 and IgA2 activity, together with total IgA, by means of an indirect immunoperoxidase technique using murine monoclonal antibodies applied to paraffin sections. The specimens showed normal histology and had been taken from patients not known to be suffering from haematological or related systemic disease. Th...

A series of 20 bone marrow trephines biopsy and necropsy specimens were stained for IgA1 and IgA2 activity, together with total IgA, by means of an indirect immunoperoxidase technique using murine monoclonal antibodies applied to paraffin sections. The specimens showed normal histology and had been taken from patients not known to be suffering from haematological or related systemic disease. Th...

Actinomyces naeslundii and Streptococcus gordonii, oral bacteria that possess Gal/GalNAc- and sialic acid-reactive lectins, respectively, were adherent to immobilized secretory immunoglobulin A (IgA) and two IgA1 myeloma proteins but not to two IgA2 myeloma proteins. Apparently, O-linked oligosaccharides at the hinge region of the IgA1 heavy chain are receptors for lectin-mediated adhesion of t...

Circulating immune complexes (CIC) containing IgA and C3 were elevated in 48% of IgA nephropathy patients; IgA1 was the predominant subclass. IgA1-IgG CIC were detected in 44%, IgA2-IgG CIC in 7%, and IgM-IgA1 CIC in 16% of the patients. No IgM-IgA2 CIC were detectable. Sucrose gradient ultracentrifugation indicated that IgG-IgA1 CIC were predominantly of intermediate (13-19S) size whereas IgA1...

To further characterize the IgA deposits found in glomeruli of patients with IgA nephropathy, anaphylactoid purpura nephritis, and systemic lupus erythematosus, renal biopsies from patients with these disorders were stained by immunofluorescence with monoclonal anti-IgA subclass reagents, anti-light chain reagents and anti-J chain. The mesangium and peripheral capillary were brightly stained fo...