Background: There are two subclasses of human IgA (IgA1 and IgA2) that differ in antigenic properties and in chemical composition. The constant domains of α1 and α2 heavy chains have >95% sequence homology though major structural differences exist in the hinge region. Quantitation of IgA subclass levels depends on the availability of monoclonal antibodies (MAbs) specific for conserved conformat...

background: there are two subclasses of human iga (iga1 and iga2) that differ in antigenic properties and in chemical composition. the constant domains of α1 and α2 heavy chains have >95% sequence homology though major structural differences exist in the hinge region. quantitation of iga subclass levels depends on the availability of monoclonal antibodies (mabs) specific for conserved conformat...

Background: There are two subclasses of human IgA (IgA1 and IgA2) that differ in antigenic properties and in chemical composition. The constant domains of α1 and α2 heavy chains have >95% sequence homology though major structural differences exist in the hinge region. Quantitation of IgA subclass levels depends on the availability of monoclonal antibodies (MAbs) specific for conserved conformat...

Human immunoglobulin (Ig)A exists in blood as two isotypes, IgA1 and IgA2, with IgA2 present as three allotypes: IgA2m(1), IgA2m(2), and IgA2m(n). We now demonstrate that recombinant, chimeric IgA1 and IgA2 differ in their pharmacokinetic properties. The major pathway for the clearance of all IgA2 allotypes is the liver. Liver-mediated uptake is through the asialoglycoprotein receptor (ASGR), s...

To understand more about the factors influencing the cleavage of immunoglobulin A1 (IgA1) by microbial IgA1 proteases, a recombinant human IgA2/IgA1 hybrid molecule was generated. In the hybrid, termed IgA2/A1 half hinge, a seven-amino-acid sequence corresponding to one half of the duplicated sequence making up the IgA1 hinge was incorporated into the equivalent site in IgA2. Insertion of the I...

To investigate the in vitro regulation of IgA subclass synthesis, peripheral blood lymphocytes from healthy adults were cultured with the polyclonal B cell activator, pokeweed mitogen. Although 50% of the IgA plasma cells from a 7-d culture were positive for cytoplasmic IgA1 and 50% were positive for IgA2, less than 10% of the IgA released into the culture supernatant was IgA2. This discrepancy...

We studied the effects of vasoactive intestinal peptide (VIP) on IgA1 and IgA2 production in human fetal B cells and pre-B cells derived from bone marrow. VIP induced IgA1, IgA2, and IgM production in sIgM+, CD19+ fetal B cells stimulated with anti-CD40 monoclonal antibody (MoAb) without inducing the production of IgG1, IgG2, IgG3, IgG4, or IgE. The anti-CD40 MoAb plus VIP also induced IgA1, Ig...

In humans, there are two subclasses of IgA, IgA1 and IgA2, with IgA2 existing as three allotypes, IgA2m(1), IgA2m(2) and IgA2(n). In IgA1, Cys(133) in C(H)1 forms the disulfide bond to the L chain. Our previous studies indicated that in IgA2 lacking Cys(133), a disulfide bond forms between the alpha-chain and the L chain when Cys(220) is followed by Arg(221), but not when Cys(220) is followed b...

Enhanced serum IgA concentrations are common in alcoholic liver cirrhosis, but functional differences between IgA subclasses and their relation with interleukin-6 (IL-6) have not been described. Distinct immunoregulatory mechanisms may exist that selectively affect one subclass. This possibility prompted us to investigate the distribution of IgA1 and IgA2 subclasses in the serum of 25 heavy alc...

Antibodies against human leukocyte antigen (HLA) class II, such as 1D10 or Lym-1, are currently being evaluated for the treatment of B-cell lymphomas. Previous studies have demonstrated that, in addition to IgG Fc receptors, the human myeloid IgA receptor (Fc(alpha)RI, CD89) also effectively triggered tumor cell killing. Therefore, we used the variable light and heavy chain sequences from anoth...