C1q-binding immunoglobulin G in MRL/l mice consists of immune complexes containing antibodies to DNA.

Previous studies have shown that the majority of C1q-binding IgG in patients with systemic lupus erythematosus (SLE) is composed of autoantibodies to the collagen-like region of C1q. Mice of the MRL/l strain are considered as a murine model of human SLE and possess autoantibodies to nuclear antigens as well as IgM and IgG rheumatoid factors (RF). This study was undertaken to characterize the C1q-binding IgG in MRL/l mice.

The structural basis of germline-encoded VH3 immunoglobulin binding to staphylococcal protein A.

The ability of human VH3 immunoglobulins (Ig) to bind to staphylococcal protein A (SPA) via their Fab region is analogous to the binding of bacterial superantigens to T cell receptors. The present report establishes the structural basis for the interaction of SPA and VH3 Ig. We have studied a panel of 27 human monoclonal IgM that were derived from fetal B lymphocytes.

Emerging human B cell repertoire. Influence of developmental stage and interindividual variation.

In B cell precursors developing in fetal lymphopoietic tissue, the selection of VH, DH, and JH gene segments for initial H chain gene assembly is biased. The present study was designed to determine whether these biases persist in fully developed human fetal B cells and to examine specificities encoded by the favored elements. B cells were prepared from two sites representing different stages of development, i.

Sequence analysis and idiotypic relationships of BEG-2, a human fetal antibody reactive with DNA.

Monoclonal antibody (mAb) BEG-2 is a dsDNA binding IgM lambda derived from a 12-week human fetus. Two binding site idiotypes (BEG-2 Id alpha and BEG-2 Id beta) have been defined with the use of polyclonal rabbit anti-idiotypic anti-serum. BEG-2 Id alpha is located on the lambda light chain and has been described previously.

A vasculopathy with deposition of lambda light chain crystals.

An 82-year-old man and a 34-year-old woman developed subacute, obstructive, fatal vasculopathies characterized by extensive crystalline tissue deposits and monoclonal lambda light chain serum components. Cryocrystalglobulinemia was also present in one patient, and the purified crystals contained only lambda light chain dimers. Although the presentation of these patients resembled that of systemic necrotizing vasculitis, histologic evidence of inflammation was lacking and their subsequent rapid clinical deterioration was not altered by corticosteroid therapy, and in one case cyclophosphamide and plasmapheresis.

Absence of auto-antiidiotypic activity between the IgM and IgG fractions of human mixed cryoglobulins.

Experimental animal models and observations in humans suggest that levels of Id and auto-anti-Id fluctuate reciprocally after Ag stimulation. In human monoclonal B cell disorders, however, the co-existence of paraprotein Id and its auto-anti-Id has been described in essential mixed cryoglobulinemia and in association with acquired C1 inhibitor deficiency. Because the majority of cryoglobulin IgM possess rheumatoid factor activity and thus bind the Fc region of IgG, we examined potential idiotypic interactions between cryoglobulin IgM and F(ab')2 fragments of autologous cryoglobulin IgG fractions.

Fc epitopes for human rheumatoid factors and the relationships of rheumatoid factors to the Fc binding proteins of microorganisms.

Work from our laboratories has shown that the major antigenic determinants for rheumatoid factors (RFs) are in the C gamma 2-C gamma 3 interface region of IgG in the same area that binds staphylococcal protein A (SPA). Furthermore, the Fc binding proteins of groups A, C and G streptococci as well as the Fc binding proteins induced on cell surfaces by herpes simplex virus type I also bind to the same area of IgG. These binding site similarities between RFs and the microbial Fc binding proteins suggested conformational similarities between the RF antigen combining regions and the Fc binding regions of the microbial proteins.

Human rheumatoid factors bear the internal image of the Fc binding region of staphylococcal protein A.

The binding specificity of rheumatoid factors (RFs) to human Fc resembles that of some microbial Fc-binding proteins, suggesting conformational similarities in their Fc-binding regions. Using polyclonal chicken antibodies against SPA, we have detected a crossreactive determinant shared by human RFs from different individuals, but not by non-RF IgM and IgG. Chicken anti-SPA was shown to bind to 18 of 19 IgM RFs and 2 of 2 IgG RFs isolated from different individuals.

Rheumatoid factors from patients with rheumatoid arthritis possess private repertoires of idiotypes.

Considerable interest has focused on idiotypic cross-reactivity among antibody molecules. Cross-reactive idiotypes (Id) on monoclonal and polyclonal rheumatoid factors (RF) have been found frequently. Sufficient attention has not been directed, however, to the proportion of RF exhibiting the cross-reactivity, leaving the impression of extensive RF cross-reactivity when, in fact, this might represent a small minority of total RF molecules in a given individual.

Development and cross-reactive properties of monoclonal antibodies to bovine matrix vesicle alkaline phosphatase.

Alkaline phosphatase (ALPase), concentrated in the membranes of matrix vesicles, is believed to play a role in initial calcification. To further purify, characterize, and identify this enzyme in tissue, a monoclonal antibody was developed against the ALPase of isolated fetal calf matrix vesicles. Splenic lymphocytes derived from mice immunized with Sepharose 6B-purified fetal calf matrix vesicle ALPase were fused with mouse plasmacytoma cells (line X63-Ag-8.

Purification and partial characterization of alkaline phosphatase of matrix vesicles from fetal bovine epiphyseal cartilage. Purification by monoclonal antibody affinity chromatography.

Alkaline phosphatase of matrix vesicles isolated from fetal bovine epiphyseal cartilage was purified to apparent homogeneity using monoclonal antibody affinity chromatography. The enzyme from the butanol extract of matrix vesicles bound specifically to the immobilized antibody-Sepharose in the presence of 2% Tween 20 whereas the major portion of nonspecific protein was removed by this single step. Of various agents tested, 0.