Evaluation of commercial amplification kit for detection of Legionella pneumophila in clinical specimens.

A commercial kit (EnviroAmp) designed to detect the DNA of Legionella species in environmental water samples using PCR and reverse dot hybridization was applied to clinical specimens. Results correlated well with culture for bronchoalveolar lavages. In addition, this test was easy to perform and showed good sensitivity

Involvement of tumor necrosis factor alpha in intracellular multiplication of Legionella pneumophila in human monocytes.

We investigated the role of tumor necrosis factor alpha (TNF-alpha) in human peripheral monocytes infected with Legionella pneumophila in vitro. Exogenous TNF-alpha significantly inhibited the intracellular multiplication of the bacterium. This effect was concentration and time dependent and was abrogated by anti-TNF antibodies. TNF-alpha levels in the culture supernatants were low but were enhanced by the addition of gamma interferon. When monocytes were cultured and infected in the presence of pentoxyphilline, a potent inhibitor of TNF-alpha synthesis, the intracellular bacterial growth was enhanced. The effect of pentoxyphilline was concentration and time dependent and was due to the inhibition of TNF-alpha production, as shown by Northern (RNA) blot hybridization of total RNA. In addition, the pentoxyphilline partially abolished the inhibitory effect of gamma interferon on bacterial intracellular multiplication. These results suggest that gamma interferon inhibits, at least partially, the intracellular multiplication of L. pneumophila by enhancing TNF-alpha synthesis

Comparison of Mycobacterium avium isolates from Greek AIDS and human immunodeficiency virus-negative patients by pulsed-field gel electrophoresis

Objective To compare the chromosomal types of Mycobacterium avium strains infecting HIV-negative and AIDS patients in Greece. Methods In total, 41 Mycobacterium avium isolates, 23 from AIDS and 18 from HIV-negative patients, were compared by pulsed-field gel electrophoresis of genomic DNA after XbaI digestion. The majority (87%) of AIDS isolates were from disseminated infection, while the majority (61%) of HIV-negative isolates were from children with cervical lymphadenitis. Results Pulsed-field gel electrophoresis classified strains whose electrophoretic patterns were at least 85% similar into three clusters, A (four isolates), B (12 isolates), and C (15), while 10 isolates remained outside of these clusters. There was no statistically significant correlation of any PFGE cluster with a specific patient group. Within each patient group, no significant correlation of PFGE type with time, place of residence or, in the case of AIDS patients, hospital attended was observed. Conclusions Genotypic similarities between isolates responsible for disseminated infection in AIDS patients and lymphadenitis in HIV-negative children suggest that related strains, possibly from an environmental source, cause both types of infections

Beneficial effect of Salmonella typhimurium infection and of immunoglobulins from S. typhimurium-infected mice on the autoimmune disease of (NZB × NZW)F1 mice

Various infections can precede or aggravate autoimmune diseases. Yet a beneficial effect of infection has also been described and various mechanisms have been postulated to explain this effect. The aim of this study was to examine the hypothesis that infection can have an immunoregulatory effect on the autoimmune process via the increased production of natural polyreactive antibodies. The effect of Salmonella typhimurium infection on the lupus-like disease of (NZB × NZW)F1 (B/W) mice was therefore studied. The effect of IgM and IgG preparations isolated from the serum of S. typhimurium-infected C57B1/6 and CBA mice on the autoimmune disease of B/W mice was also tested. C57BI/6 and CBA mice were chosen because they are respectively genetically susceptible and resistant to S. typhimurium infection and they differ in their antibody response during the early phase of infection. CBA mice can mount a specific antibacterium antibody response, whereas C57B1/6 mice present increased production of polyreactive antibodies. The infection effect was evaluated on several disease parameters, i.e. survival, incidence of high grade proteinuria and serum IgM and IgG antibody activity directed against a panel of autoantigens. Our main findings were: (i) infection of B/W mice with an attenuated strain of S. typhimurium delayed the course of the autoimmune disease when performed before the appearance of autoimmune symptoms; and (ii) IgM and IgG preparations from S. typhimurium-infected C57B1/6 mice had a similar effect, whereas the IgM and IgG preparations from infected CBA mice, as well as from normal C57B1/6 and CBA mice, were ineffective. These results suggest that S. typhimurium infection can beneficially influence the development of the autoimmune disease of B/W mice. The immunoregulatory effect of the infection seems to be related, at least partially, to the increase of a particular population of antibodies, the polyreactive antibodies

Beneficial effect of Salmonella typhimurium infection and of immunoglobulins from S. typhimurium-infected mice on the autoimmune disease of (NZB × NZW)F1 mice

Various infections can precede or aggravate autoimmune diseases. Yet a beneficial effect of infection has also been described and various mechanisms have been postulated to explain this effect. The aim of this study was to examine the hypothesis that infection can have an immunoregulatory effect on the autoimmune process via the increased production of natural polyreactive antibodies. The effect of Salmonella typhimurium infection on the lupus-like disease of (NZB × NZW)F1 (B/W) mice was therefore studied. The effect of IgM and IgG preparations isolated from the serum of S. typhimurium-infected C57Bl/6 and CBA mice on the autoimmune disease of B/W mice was also tested. C57Bl/6 and CBA mice were chosen because they are respectively genetically susceptible and resistant to S. typhimurium infection and they differ in their antibody response during the early phase of infection. CBA mice can mount a specific anti-bacterium antibody response, whereas C57Bl/6 mice present increased production of polyreactive antibodies. The infection effect was evaluated on several disease parameters, i.e. survival, incidence of high grade proteinuria and serum IgM and IgG antibody activity directed against a panel of autoantigens. Our main findings were: (i) infection of B/W mice with an attenuated strain of S. typhimurium delayed the course of the autoimmune disease when performed before the appearance of autoimmune symptoms; and (ii) IgM and IgG preparations from S. typhimurium-infected C57Bl/6 mice had a similar effect, whereas the IgM and IgG preparations from infected CBA mice, as well as from normal C57Bl/6 and CBA mice, were ineffective. These results suggest that S. typhimurium infection can beneficially influence the development of the autoimmune disease of B/W mice. The immunoregulatory effect of the infection seems to be related, at least partially, to the increase of a particular population of antibodies, the polyreactive antibodies