Autoantibodies of the cryoprecipitating IgG3 isotype have been shown to play a significant role in the development of murine lupus-like autoimmune syndrome. At present, the structural basis of IgG3 cryoprecipitation and its role in autoantibody pathogenicity remain to be defined. Using molecular variants of an IgG3 monoclonal rheumatoid factor, 6-19, derived from an autoimmune MRL-Fas(lpr) mous...

ABL 364 is a murine monoclonal IgG3 antibody directed against the Lewis Y carbohydrate antigen (Le(y)) expressed on the surface of many epithelial cell tumors. The antibody mediates cytotoxicity via activation of human complement or human effector cells, and has been evaluated in several clinical trials including two Phase I/II trials in relapsed small cell lung cancer and metastatic breast can...

The middle part of the heavy chain of IgG3 (hinge region) which covalently links the two y3 chains to each other, is about 4 times larger than the same region in the three other human IgG subclasses. This is probably due to a quadruplication of a 45-nucleotide DNA segment resulting in a y3 hinge region which is 62 amino acid residues long and consists of an NH,-terminal 17-residue segment follo...

Serum IgG subclass levels were measured using an indirect immunoenzymatic assay (ELISA) with monoclonal antibodies in 16 children with asthma and 13 children with atopy who had mostly recurrent infections. Seven of the asthmatic children had marked low or low normal levels of IgG4, six had marked low or low normal levels of IgG 3, two had marked low normal levels of both IgG2, and IgG 3 and...

The subclass specificities of antiviral immunoglobulin G (IgG) produced in response to herpes simplex and varicella-zoster virus infections were investigated. IgG1 and IgG3 with anti-herpes simplex virus activity were seen in patients with primary and reactivated disease, as well as in healthy seropositive subjects and in immunoglobulin preparations. IgG4 was occasionally seen alone or together...

Using two different kinds of monoclonal autoantibodies, anti-mouse RBC (MRBC) autoantibodies and IgG3 rheumatoid factor (RF) cryoglobulins, we have attempted to better define the molecular and cellular basis of the pathogenicity of autoantibodies. Among eight anti-MRBC monoclonal antibodies (mAbs) obtained from NZB mice, only five of them are able to cause anemia. The distinct differences in sp...

The kinetics of the humoral immune response was evaluated using the recombinant SAG2A protein comparatively to soluble Toxoplasma antigen (STAg) by ELISA in sequential serum samples of patients with toxoplasmosis up to 12 months of illness onset. The follow up of IgM and IgA levels to STAg showed a gradual decrease, with the majority of patients (88%) seropositive for IgM up to 12 months of inf...

Three classes of IgG have been described for camelids. IgG1 has a conventional four-chain structure, while IgG2 and IgG3 do not incorporate light chains. The structures and antigen-binding affinities of the so-called heavy-chain classes have been studied in detail; however, their regulation and effector functions are largely undefined. The aim of this study was to examine the participation of c...

BACKGROUND & OBJECTIVES Earlier we demonstrated that immunization with F6, a proinflammatory molecular fraction isolated from the human filarial parasite Brugia malayi, protected the host and eliminated the infection in Mastomys coucha by a Th1/Th2 response including IgG2a antibody response. Whether F6 molecules become accessible to human host during natural course of infection and elicit simil...