Bacterial flora of the low male genital tract in patients consulting for infertility.

The physiological aerobic bacterial flora of the low male genital tract was determined. This prospective study was performed on 600 semen specimens collected from 543 asymptomatic males consulting for infertility. Semen cultures were sterile in 28.8%, with a polymicrobial flora and/or absence or low titres of Ureaplasma urealyticum in 49.3%, and with one or two aerobic and facultative bacteria > or =1 x 10(3) CFU ml(-1) and/or U. urealyticum with titres > or =10(4) CCU ml(-1) (colour changing units) in 21.8%. In standard aerobic cultures, Gardnerella vaginalis was the most commonly isolated species (26.1%), followed by coagulase-negative staphylococci (15.7%) and Streptococcus anginosus (14.2%). Ureaplasma urealyticum was absent in 84.5% of semen samples, but when recovered, high (> or =10(4) CCU ml(-1)) and low titres (< or =10(3) CCU ml(-1)) were counted in 7.2% and 8.3% respectively. Of 48 patients, the follow-up of semen cultures showed marked variations in time. This study shows that (i) there was no relationship between the bacterial flora and the leucocytospermia; (ii) low titres of U. urealyticum in semen were not associated with a disturbance of the ecosystem; (iii) the critical threshold for U. urealyticum should be raised to > or =10(4) CFU ml(-1) and (iv) a positive semen culture should be repeated before any treatment.

IgG reactivity against citrullinated myelin basic protein in multiple sclerosis.

An increased level of citrullinated myelin basic protein (MBP-C8) has been reported in the brains of multiple sclerosis (MS) patients. However, the involvement of the immune response to post-translational modified MBP in the pathophysiology of MS remains speculative. The aim of this study was to compare the levels of immunoglobulin G antibodies to several MBP epitopes, before and after citrullination, in the cerebrospinal fluid (CSF) and sera of MS patients using enzyme-linked immunosorbent assay (ELISA). We analyzed antibody reactivity against various MBP-peptides in the CSF and sera of 60 MS patients, and 30 patients with other neurological diseases (OND) as controls. The peptides tested were: MBP(75-98) (peptide 1), native (peptide 2) and citrullinated (peptide 3) MBP(108-126) (ARG(122)-->Cit(122)), and native (peptide 4) and citrullinated (peptide 5) MBP(151-170) (ARG(159, 170)-->Cit(159, 170)). All selected peptides could support an immune reactivity in CSF and sera of MS and OND patients. A higher reactivity against peptide 4 was found in the CSF of MS patients compared with OND patients (P<0.0001), but not against citrullinated peptides (peptides 3 and 5). However, we observed that the citrullination state of peptide 2 modified the patterns of immune reactivity more markedly in MS patients (P<0.0001) than in OND patients (P<0.02). Although some MBP epitopes could be a potential target in MS, our data did not demonstrate any difference of antibody response to MBP peptides in their citrullinated forms.

Coordinate involvement of invasin and Yop proteins in a Yersinia pseudotuberculosis-specific class I-restricted cytotoxic T cell-mediated response.

Yersinia pseudotuberculosis is a pathogenic enteric bacteria that evades host cellular immune response and resides extracellularly in vivo. Nevertheless, an important contribution of T cells to defense against Yersinia has been previously established. In this study we demonstrate that Lewis rats infected with virulent strains of Y. pseudotuberculosis, mount a Yersinia-specific, RT1-A-restricted, CD8+ T cell-mediated, cytotoxic response. Sensitization of lymphoblast target cells for cytolysis by Yersinia-specific CTLs required their incubation with live Yersinia and was independent of endocytosis. Although fully virulent Yersinia did not invade those cells, they attached to their surface. In contrast, invasin-deficient strain failed to bind to blast targets or to sensitize them for cytolysis. Furthermore, an intact virulence plasmid was an absolute requirement for Yersinia to sensitize blast targets for cytolysis. Using a series of Y. pseudotuberculosis mutants selectively deficient in virulence plasmid-encoded proteins, we found no evidence for a specific role played by YadA, YopH, YpkA, or YopJ in the sensitization process of blast targets. In contrast, mutations suppressing YopB, YopD, or YopE expression abolished the capacity of Yersinia to sensitize blast targets. These results are consistent with a model in which extracellular Yersinia bound to lymphoblast targets via invasin translocate inside eukaryotic cytosol YopE, which is presented in a class I-restricted fashion to CD8+ cytotoxic T cells. This system could represent a more general mechanism by which bacteria harboring a host cell contact-dependent or type III secretion apparatus trigger a class I-restricted CD8+ T cell response.