Induction of “wire-loop” lesions by murine monoclonal IgG3 cryoglobulins

Abstract

We have recently demonstrated that an IgG3 rheumatoid factor (RF) monoclonal antibody (mAb), clone 6-19, derived from unmanipulated autoimmune MRL/MpJ-lpr/lpr mice, is able to generate cryoglobulins via a non-immunological IgG3 Fc interaction, and to induce an acute glomerulonephritis associated with cryoglobulinemia. Using this experimental model, we have characterized the glomerular lesions induced by the 6-19 RF monoclonal cryoglobulin, in particular the ultrastructural localization of the cryoglobulin deposits. Although their initial localization was confined to the mesangium, the 6-19 cryoglobulins were progressively accumulated in the subendothelial spaces of glomerular capillary walls, leading to the formation of glomerular lesions resembling the "wire-loop" lesion characteristically described for lupus nephritis. In addition, we have found that identical glomerular "wire-loop" lesions were induced by the 6-19-J558 hybrid antibody, composed of the 6-19 gamma 3 heavy chain and J558 lambda 1 light chain, which loses the RF activity, but retains the cryoglobulin activity. These results strongly suggest that the direct deposition of IgG3 cryoglobulins by itself, without involvement of immune complex formation, results in the generation of the classical "wire-loop" lesion characteristic of lupus nephritis. In addition, we have found that similar "wire-loop" lesions were generated by one anti-DNA mAb derived from (NZB x NZW)F1 hybrid mice, and two of four IgG3 mAb of unknown specificities, derived from MRL/MpJ-lpr/lpr mice. The absence of significant glomerular lesions, in spite of large amounts of cryoglobulins, in mice receiving two IgG3 mAb suggests the importance of physicochemical property of cryoglobulins to provoke glomerular lesions.

Complement Component C3 Is Not Required for Full Expression of Immune Complex Glomerulonephritis in MRL/lprMice

“…It is also known that MRL/lpr renal disease and vasculitis are linked with IgG3 cryoglobulin production (28,29,32,33). We measured serum levels of total IgG and IgG3 by ELISA and found no statistically significant differences among the three groups (Fig.…”

Dominant NZB contributions to lupus in the (SWR×NZB)F1 model

“…33 The following phenotypes were used for linkage analysis: serum IgG ANAs, IgM Abs, total serum IgG3, histological GN, and age of death. Since IgG3 has been associated with cryoglobulinemia and consequent renal disease, 34,35 this phenotype was also analyzed in the present study. The ANA specificities that were examined are detailed below.…”

An experimental model of cryoglobulin-associated vasculitis in mice

“…It should be emphasized, however, that only a fraction of IgG3 monoclonal cryoglobulins with other specifieities are able to provoke significant glomerular lesions, independently of serum levels of cryoglobulins [15,16,22]. This would well explain the fact that the quantity of circulating cryoglobulins does not always correlate with the degree of nephropathy in patients with cryoglobulinemia [45].…”

“…To address this question, we have assessed the ability of IgG3 monoclonal antibodies (mAb) from autoimmune MRL-Ipr/lpr and (NZB x NZW)FI mice to generate cryoglobulins. Out of 32 IgG3 mAb, independent of their immunological specificities, 28 are capable of generating cryoglobulins composed exclusively of each IgG3 mAb without the intervention of any antigens, and are thus classified as type I monoclonal cryoglobulins [14][15][16]. The importance of the 73 constant (C73) region for cryoglobulin generation has been most directly demonstrated by Ig class-switch experiments: the cryoglobulin activity is gained following the lg class switch of mAb from tgM to lgG3, but lost following the class switch from [gG3 to IgM or lgG1 [14,.…”

“…The 6-19 IgG3 anti-lgG2a RF mAb, derived from MRL-lpr/lpr mice, induces a remarkable pathology [15,16]. At 5--7 days after the injection of 6-19 IgG3 RF hybridoma, vascular purpura, which is the most common manifestation in patients with cryoglobulinemia [3], develops in the skin of the ears, tails and footpads, which are not well protected by hair from thermic variations.…”