Human IgG3 displays the strongest effector functions of all IgG subclasses but has a short half-life for unresolved reasons. Here we show that IgG3 binds to IgG-salvage receptor (FcRn), but that FcRn-mediated transport and rescue of IgG3 is inhibited in the presence of IgG1 due to intracellular competition between IgG1 and IgG3. We reveal that this occurs because of a single amino acid differen...

A transplantable plasma cell leukemia cell line, designated as S27, was established from a 12-month-old female New Zealand Black mouse (NZB); serum showed polyclonal elevation of gamma globulin with agarose-agar gel electrophoresis. Immunoelectrophoretic analysis of the serum showed precipitation lines in the IgG1, IgG2a, IgG2b and IgM regions. The amount of serum immunoglobulin increased rapid...

Clearance of immune complexes made of antiinsulin antibodies and 123I-insulin was studied with scintillation scanning in anesthetized rats. Complexes made with purified guinea pig antiinsulin IgG2 (cytophilic isotype) were rapidly cleared by the liver whereas those made with IgG1 remained in the plasma, as did 123I-labeled IgG1 or IgG2 of control animals. Hepatic clearance of insulin-antiinsuli...

We have constructed a protein composed of a soluble single-chain TCR genetically linked to the constant domain of an IgG1 H chain. The Ag recognition portion of the protein binds to an unmutated peptide derived from human p53 (aa 264-272) presented in the context of HLA-A2.1, whereas the IgG1 H chain provides effector functions. The protein is capable of forming dimers, specifically staining tu...

A group of 16 patients with a disproportionate polyclonal increase in their serum IgG1, resulting in raised concentrations of total IgG immunoglobulin, has been discovered. The other IgG subclasses in these patients are either normal or slightly reduced, resulting in an IgG1:IgG2 ratio of at least 10:1. Most cases are marked by the presence of anti-extractable nuclear antigen (anti-ENA) antibod...

We have determined whether B cells previously activated by anti-Ig (anti-Ig blasts) are responsive to lymphokines that induce isotype switching. Culture of anti-Ig blasts with a mixture of lymphokines, including BSF-1, resulted in marked secretion of IgM and IgG1, but not other IgG isotypes. The IgG1 response of anti-Ig blasts to lymphokines was 13-fold greater than was observed with splenic B ...

OBJECTIVE To evaluate the immunoglobulin G subclasses of anti-TPO and antibody avidity in patients with subclinical hypothyroidism (sH), overt hypothyroidism (H) and a control group (C). METHODS According to the TSH, fT4 and anti-TPO antibody levels, appraised by immunometric assays, 95 female patients were divided into three groups (sH, H and C). IgG subclass levels and avidity were measured...

The binding sites on human IgG1 for human Fc gamma receptor (Fc gamma R) I, Fc gamma RIIa, Fc gamma RIIb, Fc gamma RIIIa and neonatal FcR have been mapped. A common set of IgG1 residues is involved in binding to all Fc gamma Rs, while Fc gamma RII and Fc gamma RIII utilize distinct sites outside this common set. In addition to residues which abrogated binding to the Fc gamma R, several position...

A systematic study following infection by various strains of the protozoan parasite, Trypanosoma cruzi, and the simultaneous monitoring of the humoral immune response together with the elicited cellular response, could add greatly to our understanding of differences between strains of this important human pathogen. In that sense, acute and chronic infections with distinct T. cruzi strains (Y, B...

This research investigated the profile of anti-Leishmania antibodies in different clinical forms of canine visceral leishmaniasis (CVL). Naturally infected dogs were divided into two groups: subclinical dogs (SD, n=10) and clinical dogs (CD, n=68). Non-infected dogs (ND, n=7) comprised the negative control group. The humoral response was evaluated by the profile of total IgG, IgG1, IgG2, IgM, I...