Intravenous Injection of a D1 Protein of the Smith Proteins Postpones Murine Lupus and Induces Type 1 Regulatory T Cells

T cells that recognize nucleoproteins are required for the production of anti-dsDNA Abs involved in lupus development. SmD1 83-119 (a D1 protein of the Smith (Sm) proteins, part of small nuclear ribonucleoprotein) was recently shown to provide T cell help to anti-dsDNA Abs in the NZB/NZW model of lupus. Using this model in the present study, we showed that high dose tolerance to SmD1 (600-1000 microg i.v. of SmD1(83-119) peptide/mo) delays the production of autoantibodies, postpones the onset of lupus nephritis as confirmed by histology, and prolongs survival. Tolerance to SmD1 83-119 was adoptively transferred by CD90+ T cells, which also reduce T cell help for autoreactive B cells in vitro. One week after SmD1 83-119 tolerance induction in prenephritic mice, we detected cytokine changes in cultures of CD90+ T and B220+ B cells with decreased IFN-gamma and IL-4 expression and an increase in TGFbeta. Increased frequencies of regulatory IFN-gamma+ and IL10+ CD4+ T cells were later detected. Such regulatory IL-10+/IFN-gamma+ type 1 regulatory T cells prevented autoantibody generation and anti-CD3-induced proliferation of naive T cells. In conclusion, these results indicate that SmD1 83-119 peptide may play a dominant role in the activation of helper and regulatory T cells that influence autoantibody generation and murine lupus.

CC chemokine receptor 5 and renal-transplant survival

BACKGROUND

About 1% of white populations are homozygous carriers of an allele of the gene for the CC chemokine receptor 5 (CCR5) with a 32 bp deletion (CCR5Delta32), which leads to an inactive receptor. During acute and chronic transplant rejection, ligands for CCR5 are upregulated, and the graft is infiltrated by CCR5-positive mononuclear cells. We therefore investigated the influence of CCR5Delta32 on renal-transplant survival.

METHODS

Genomic DNA from peripheral-blood leucocytes of 1227 renal-transplant recipients was screened by PCR for the presence of CCR5Delta32. Demographic and clinical data were extracted from hospital records. Complete follow-up data were available for 576 recipients of first renal transplants. Graft survival was analysed by Fisher's exact test and Kaplan-Meier plots compared with a log-rank test.

FINDINGS

PCR identified 21 patients homozygous for CCR5Delta32 (frequency 1.7%). One patient died with a functioning graft. Only one of the remaining patients lost transplant function during follow-up (median 7.2 years) compared with 78 of the 555 patients with a homozygous wild-type or heterozygous CCR5Delta32 genotype. Graft survival was significantly longer in the homozygous CCR5Delta32 group than in the control group (log-rank p=0.033; hazard ratio 0.367 [95% CI 0.157-0.859]).

INTERPRETATION

Patients homozygous for CCR5Delta32 show longer survival of renal transplants than those with other genotypes, suggesting a pathophysiological role for CCR5 in transplant loss. This receptor may be a useful target for the prevention of transplant loss.

Characterization of two human IgM monoclonal antibodies reactive with HLA-B27

We describe here the generation and characterization of two human monoclonal IgM antibodies (UL-4F11 and UL-F6) reactive with HLA-B27. The monoclonal antibody (mAb) UL-4F11 is cytotoxic for peripheral mononuclear cells and, therefore, useful as typing reagent for HLA-B27 and HLA-B38. Protein chemistry showed that the mAb UL-4F11 precipitates HLA-B27 molecules. Epitope mapping analysis suggests that the amino acids 45, 67, 82 and 83 (alpha-1 domain) of the HLA-B27 sequence are necessary for mAb UL-4F11 reactivity. The mAb UL-F6 is suitable for complement dependent lysis of lymphoblastoid cell lines and stimulated peripheral blood mononuclear cells with HLA-B27 (B*2701, B*2702, B*2703, B*2705, B*2707), B13, B40 (60,61), B47 and B48 specificities. Its reactivity indicates that the amino acid valine in position 152 and glutamic acid in position 163 of the alpha-2 domain are crucial for the binding epitope.