Anti-huCD20 antibody therapy for antibody-mediated rejection of renal allografts in a mouse model.

We have reported that B6.CCR5(-/-) mice reject renal allografts with high serum donor-specific antibody (DSA) titers and marked C4d deposition in grafts, features consistent with antibody-mediated rejection (AMR). B6.huCD20/CCR5(-/-) mice, where human CD20 expression is restricted to B cells, rejected A/J renal allografts by day 26 posttransplant with DSA first detected in serum on day 5 posttransplant and increased thereafter. Recipient treatment with anti-huCD20 mAb prior to the transplant and weekly up to 7 weeks posttransplant promoted long-term allograft survival (>100 days) with low DSA titers. To investigate the effect of B cell depletion at the time serum DSA was first detected, recipients were treated with anti-huCD20 mAb on days 5, 8, and 12 posttransplant. This regimen significantly reduced DSA titers and graft inflammation on day 15 posttransplant and prolonged allograft survival >60 days. However, DSA returned to the titers observed in control treated recipients by day 30 posttransplant and histological analyses on day 60 posttransplant indicated severe interstitial fibrosis. These results indicate that anti-huCD20 mAb had the greatest effect as a prophylactic treatment and that the distinct kinetics of DSA responses accounts for acute renal allograft failure versus the development of fibrosis.

B cell activating factor (BAFF) and a proliferation inducing ligand (APRIL) mediate CD40-independent help by memory CD4 T cells.

Donor-reactive memory T cells undermine organ transplant survival and are poorly controlled by immunosuppression or costimulatory blockade. Memory CD4 T cells provide CD40-independent help for the generation of donor-reactive effector CD8 T cells and alloantibodies (alloAbs) that rapidly mediate allograft rejection. The goal of this study was to investigate the role of B cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) in alloresponses driven by memory CD4 T cells. The short-term neutralization of BAFF alone or BAFF plus APRIL synergized with anti-CD154 mAb to prolong heart allograft survival in recipients containing donor-reactive memory CD4 T cells. The prolongation was associated with reduction in antidonor alloAb responses and with inhibited reactivation and helper functions of memory CD4 T cells. Additional depletion of CD8 T cells did not enhance the prolonged allograft survival suggesting that donor-reactive alloAbs mediate late graft rejection in these recipients. This is the first report that targeting the BAFF cytokine network inhibits both humoral and cellular immune responses induced by memory CD4 T cells. Our results suggest that reagents neutralizing BAFF and APRIL may be used to enhance the efficacy of CD40/CD154 costimulatory blockade and improve allograft survival in T cell-sensitized recipients.

Effector functions of donor-reactive CD8 memory T cells are dependent on ICOS induced during division in cardiac grafts.

Alloreactive T-cell memory is present in every transplant recipient and endangers graft survival. Even in the absence of known sensitizing exposures, heterologous immunity and homeostatic T-cell proliferation generate 'endogenous' memory T cells with donor-reactivity. We have recently shown that endogenous donor-reactive CD8 memory T cells infiltrate murine cardiac allografts within hours of reperfusion and amplify early posttransplant inflammation by producing IFN-gamma. Here, we have tested the role of ICOS co-stimulation in eliciting effector function from these memory T cells. ICOS is not expressed on the cell surface of circulating CD8 memory T cells but is rapidly upregulated during cell division within the allograft parenchyma. Donor-reactive CD8 memory T-cell infiltration, proliferation and ICOS expression are regulated by donor class I MHC molecule expression. ICOS blockade significantly reduced IFN-gamma production and other proinflammatory functions of the activated CD8 memory T cells. Our data demonstrate that this induction of ICOS expression within peripheral tissues is an important feature of CD8 memory T-cell activation and identify ICOS as a specific target for neutralizing proinflammatory functions of endogenous CD8 memory T cells.

Inhibition of VSV and EMCV replication by the interferon-induced GTPase, mGBP-2: differential requirement for wild-type GTP binding domain.

Interferons (IFNs) exert their anti-viral activities through the induction of anti-viral proteins. One member of the guanylate binding protein (GBP) family of IFN-induced GTPases, hGBP-1, has previously been shown to contribute to the antiviral activities of IFNs. Murine GBP-2 inhibited the replication of both vesicular stomatitis virus (VSV) and encephalomyocarditis virus (EMCV). A wild type GTP binding motif was not required for VSV inhibition but was required for inhibition of EMCV. This is the first demonstration of the role of enzymatic activity in the antiviral activities of GBPs and these findings suggest different mechanisms of inhibition for the two viruses.

Restricted growth of ent(-) and tonB mutants of Salmonella enterica serovar Typhi in human Mono Mac 6 monocytic cells.

Monocytes and macrophages are an important host defense in humans infected with Salmonella enterica serovar Typhi. Bacterial ability to survive in these cells is therefore a crucial virulence characteristic of this pathogen. In this study, we demonstrate that growth of a Salmonella enterica serovar Typhi enterochelin synthesis mutant and a tonB mutant in the human monocyte cell line Mono Mac 6 is restricted compared to that of the parental wild-type Ty2 strain. These results suggest that enterochelin- and TonB-mediated iron uptake plays a role in S. enterica serovar Typhi pathogenesis, and also suggest that mutations in iron uptake may attenuate S. enterica serovar Typhi strains for human beings.

Different subcellular localizations for the related interferon-induced GTPases, MuGBP-1 and MuGBP-2: implications for different functions?

The guanylate-binding proteins (GBPs) are a family of 65-67-kDa proteins induced by both type I and type II interferons (IFN). Members of the GBP family of GTPases are among the most abundant IFN-gamma-induced proteins. GBPs contain an unusual GTP binding site, which is consistent with GBP hydrolysis of GTP to both GDP and GMP. In addition, six of the eight known GBPs have a carboxy-terminal CaaX motif for the addition of isoprenyl lipids. Despite their abundance, however, little is known about the biologic function or cellular location of GBPs. We report here on studies to localize both a newly identified murine GBP (MuGBP-2) and its closely related family member, MuGBP-1. In both IFN-treated macrophages and fibroblasts, MuGBP-2 is found in both a granular distribution throughout the cytoplasm and localized to vesicle populations of heterogeneous sizes. The localization of MuGBP-2 to vesicles is dependent on its isoprenylation. Despite a high degree of sequence identity and the presence of an identical CaaX sequence, MuGBP-1 has a very homogeneous cytoplasmic distribution and fails to localize to intracellular vesicles. The different intracellular distribution of these two closely related family members suggests differential function(s).

Analysis of the bmp gene family in Borrelia burgdorferi sensu lato.

BmpA, BmpB, BmpC, and BmpD are homologous Borrelia burgdorferi lipoproteins of unknown functions, encoded by the bmp genes of paralogous chromosomal gene family 36. At least some of the Bmp proteins are immunogens in infected vertebrate hosts. The genetic organization of the bmp region has been characterized for a variety of B. burgdorferi sensu lato strains by Southern hybridization, PCR amplification, and DNA sequencing. All four bmp genes were present in the same relative order in all B. burgdorferi sensu lato low- and high-passage-number isolates. While there were no differences in the relative orders of the bmp genes in these species, variations in DNA sequence in the bmpD-bmpC and bmpC-bmpA intergenic regions were significantly more common than in the corresponding 3' bmpD and bmpC coding regions. The genetic structure of the chromosomal region containing the bmp genes thus appears to be well conserved across different species of B. burgdorferi, but variations in DNA fine structure that prevent PCR primer annealing may occur in this region and make Southern hybridization much more reliable than PCR for detection of the presence of these genes. Our results also suggest that bmp gene products may be used as reagents in the preparation of vaccines and diagnostic assays to protect against and diagnose Lyme disease produced by B. burgdorferi sensu lato.

[Effectiveness of the decontaminating action of disinfectants on Klebsiella ozaenae-contaminated surfaces]. / Effektivnost' obezzarazhivaiushchego deistviia nekotorykh dezinfektantov na kontaminirovannykh Klebsiella ozaenae poverkhnostiakh.

The effectiveness of the disinfecting action of elevated temperature (59 degrees C and 100 degrees C), chloraemine, chlorhexidine, sodium dichlorisocyanurat, hydrogen peroxide, nirtan and phenol on surfaces contaminated with K. ozaenae has been studied. These organisms have been found to be highly susceptible to the action of elevated temperature and the tested disinfectants. The effective concentrations of these disinfectants and exposure time are recommended for routine disinfection in the foci of ozena.

[Epidemiological problems of ozena and the means for controlling this infection]. / Voprosy épidemiologii ozeny i puti bor'by s étoi infektsiei.

Clinical, bacteriological, serological and epidemiological studies of ozena morbidity among the population of Minsk were carried out in 1970-1980. On January 1, 1981, the ozena morbidity rate among the inhabitants of Minsk was 26.72%. Ozena was found to affect mainly children and women. A wide spread of the family foci of this disease (31.68%) was revealed. The results of this study indicate that the source of K. ozaenae is a sick person who begins to excrete the bacteria in the prodromal period of the disease and may continue to excrete them for many years. The transfer of K. ozaenae occurs probably by droplet or contact infection. The droplet infection is less active in the absence of symptoms (coughing, sneezing) facilitating excretion of the infective agent into the air and in cases of the low susceptibility of persons to ozena. The main measures for controlling ozena are the timely detection and sanitation of the sources of ozena, as well as the current disinfection of the infection foci in apartments.