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Biomedical subjects

R C Monteiro

Publications and source records attributed to R C Monteiro.

41 records · Page 3Linked to original sources
PubMed1987

Altered cell-surface protein(s), crossreactive with DNA, on spleen cells of autoimmune lupic mice.

A murine monoclonal anti-DNA antibody, PME77, with specificity for double-stranded DNA, has previously been shown to react with a protein(s) present at the surface of such cells involved in lupus pathogenesis as human glomeruli, T and B lymphocytes, erythrocytes, and platelets. Mild elastase treatment of lymphoid cells from non-autoimmune (CBA/ca or BALB/c) mice releases a series of crossreactive polypeptides (34, 33, 17, 16, and 14 kDa) recognized by PME77. These polypeptides are not formed after treatment of the same cells with papain or trypsin. When lymphoid cells from autoimmune [MRL-lpr/lpr or (NZB X NZW)F1 B/W] mice are treated with elastase, trypsin, or papain, PME77 detects, in all supernatants, a single polypeptide of about 55 kDa. Antibodies present in the sera of autoimmune MRL-lpr/lpr and B/W mice and IgG eluted from kidneys of MRL-lpr/lpr mice react with the same polypeptides. Neither sera nor eluted IgG of normal BALB/c mice react with these polypeptides. These results suggest that an altered cell-surface protein(s), which we call LAMP [for lupus-associated membrane protein(s)], may be involved in lupus pathogenesis.

Animals↗
PubMed1987

Induction of Fc receptors for IgA on murine T cell hybridoma by human monoclonal IgA and by high molecular weight IgA in IgA nephropathy.

A reproducible immunocyto-adherence assay has been developed to study the modulation of Fc receptors for IgA (Fc alpha R), using a murine T cell hybridoma (T2D4), which expresses Fc receptors for all known isotypes of secreted immunoglobulins. By using sheep red blood cells coated with the hapten 2-4-6 trinitrophenyl (TNP), as indicator cells, and a murine monoclonal IgA (MOPC 315) antibody with anti-TNP activity, we were able to study the Fc alpha R on T2D4 cells. We found that: (a) murine Fc alpha R can bind human monoclonal IgA, and this binding is isotype specific since it was inhibited by human monoclonal IgA but not by human monoclonal IgG or IgM; (b) the expression of murine Fc alpha R is unducible by human monoclonal IgA, and this effect is isotype specific since it is not observed with human monoclonal IgM or IgG (c) sera from patients with IgA nephropathy can also induce Fc alpha R expression; by contrast, no induction was observed with normal human sera, (d) in one serum from an IgA-nephropathy patient, the inducer factor was characterized by affinity chromatography on anti-IgA-Sepharose and by gel filtration: high molecular weight IgA, probably IgA aggregates or immune complexes were recognized to be responsible for the induction of murine Fc alpha R expression.

Animals↗
PubMed1986

[Pathogenic antibodies in systemic lupus erythematosus: anti-LAMP antibodies].

We recently demonstrated that a monoclonal anti-DNA antibody, spontaneously produced in lupus B/W mice, recognizes the same protein(s) at the surface of several human cell types involved in lupus pathogenesis including normal human erythrocytes, normal platelets and rat neuronal tissue. This cell-surface protein(s) cross-react(s) with double-stranded DNA. We suggest to call this protein(s) LAMP [lupus associated membrane protein(s)]. Here we show that: immunoglobulins eluted from kidneys of autoimmune MRL/lpr/lpr mice strongly react with LAMP. Anti-LAMP antibodies are present in large amount in MRL/lpr and B/W mice sera. Anti-LAMP are present in 25 out of 25 human SLE sera ranged as SLE on the basis of revised American Rheumatism Associated classification. Interestingly, two of these sera did not display anti DNA anti-body activity. Taken together, these results strongly suggest a role of LAMP in the pathogeny of SLE.

Animals↗
PubMed1985

Charge and size of mesangial IgA in IgA nephropathy.

To characterize the physicochemical properties of the mesangial IgA in primary IgA nephropathy, acid-eluates from percutaneous renal biopsies of 20 patients were examined. The acid-eluates were obtained from 1287 +/- 498 glomerular sections. The IgA content (mean 15 +/- 10 ng) represented 0.4% of the total eluted proteins. To analyze the molecular weight and the charge of eluted IgA, 11 eluates were subjected to high pressure liquid chromatography (at pH 6.8 and/or pH 3.5) and five eluates to isoelectric focusing on agarose. IgA was detected in the fractions by an IgA-RIA. Comparison of the elution profiles at different pH showed a statistically significant decrease of the excluded IgA peak (greater than or equal to 1,000,000 daltons), and a significant increase of polymeric IgA peaks (1,000,000-320,000 and 320,000 daltons) in acidic chromatography, as compared to non-dissociating conditions. Under acidic conditions, polymeric IgA represent 64% of total eluted IgA. Secretory component binding to polymeric IgA was demonstrated in four out of eight eluates tested. The isoelectric point (pI) of eluted IgA ranged from 4.5 to 5.6, contrasting with the broader and more neutral pI of normal serum IgA (4.5 to 6.8). This study shows that the multimeric nature of IgA, the formation of IgA complexes, and the anionic charge of IgA are likely to be involved in the mesangial IgA deposition in idiopathic IgA nephropathy.

Adolescent↗