Inhibition of lymphocyte-mediated antibacterial activity by human seminal plasma.

Seminal plasma displays a suppressive function on many immunological responses. In light of recent findings on the antibacterial activity mediated by different lymphocyte subsets, we have assessed the effect of male inhibitory material (MIM) in this system. Results provide evidence that MIM pretreatment of peripheral blood lymphocytes (PBL) leads to a significant inhibition of antibacterial activity against Salmonella typhi and S. minnesota R345 (Rb). Both CD4+ and CD8+ cell-mediated activities are reduced by this treatment, while another defense mechanism (bacterial binding to PBL) is unaffected. Taken together, these results indicate a role for MIM in the depression of immune response and suggest that lymphocytes mediating antibacterial activity and bacterial cytoadherence are different entities.

Lymphocyte-Salmonella interaction: energy dependence and thiol group involvement.

In order to gain better insight into lymphocyte-Salmonella interaction investigation has been carried out on energy-dependence and involvement of thiol groups in this process by using a modified rosette test. Binding frequency, number of bound bacteria/number of binding lymphocytes and the number of bacteria-binding sites/lymphocyte were found to be enhanced by externally added ATP and decreased by both uncouplers and electron transfer chain inhibitors. Treatment of either bacteria or lymphocytes with thiol reagents, such as mersalyl or N-ethyl-maleimide, prevents lymphocyte-Salmonella adherence, thus showing the presence of thiol groups involved in the binding mechanism in both bacteria and cells. Consistently, as a result of mersalyl inhibition, a decrease in the number of bacteria-binding sites/lymphocyte was also found.

Phagocytosis of Leishmania infantum promastigotes by monocytes isolated from Leishmania-infected dogs.

Fifteen dogs with generalised leishmaniasis have been evaluated for their monocyte capacity to ingest Leishmania promastigotes. These cells displayed a lower phagocytic ability when compared to monocytes recovered from normal dogs. Moreover, sera from Leishmania-infected dogs caused a remarkable decrease of monocyte phagocytic ability in healthy dogs, whereas sera from healthy dogs could restore monocyte phagocytosis in sick animals. Similar results were seen when Candida albicans was used as stimulant. Interestingly, supernatants from polyethylenglycole (PEG) treated sera from Leishmania-infected dogs did not inhibit monocyte phagocytosis either in the autologous or in the homologous (healthy dogs) system. This suggests a possible role for serum factor(s) in the impairment of phagocytosis in Leishmania infection.

[Biochemical aspects of lymphocyte metabolism. Immunomodulating role of cyclic nucleotides]. / Aspetti biochimici del metabolismo linfocitario. Ruolo immunomodulante dei nucleotidi ciclici.

In the present review lymphocyte metabolism has been examined with particular reference to ion and molecule flux variations through cell membrane. Furthermore, mitogenic stimulations causes a tremendous increase of cellular metabolism with remarkable modifications of oxidative processes and synthesis rate of enzymes and structural proteins. Finally, the role of cyclic nucleotides in the regulation of some lymphocyte functions has been analyzed.

Relationship between immune system and gram-negative bacteria. Acid-treated Salmonella minnesota R595 (Re) enhances immune responsiveness in patients with gynecologic malignancies.

Nine patients with gynecologic malignancies (six cervix, two endometrium and one ovary) were injected with acid-treated Salmonella minnesota R595 (Re). Patients received a total of four injections (at increasing doses from 0.5 to 3 micrograms) every 2 weeks. All patients, before treatment, had a severe impairment of their immune system either of cell-mediated immunity (leukocyte inhibiting factor activity) or non-specific immunity (polymorphonuclear cell and/or monocyte-mediated phagocytosis and killing). In contrast, the same patients displayed a normal Natural Killer cell frequency in their peripheral blood as evaluated in an agarose-single cell cytotoxic assay. At the end of the immunotherapeutic regimen, all the above immune functions significantly augmented likely via an immunomodulating effect exerted by the lipid A portion of Salmonella minnesota Re which represents the lipopolysaccharide molecule in these bacteria. This suggests a potential role for lipid A in the treatment of cancer-related immunodeficiency.

Quantitative analysis of lymphocyte-Salmonella interaction and effect of lymphocyte irradiation by Helium-Neon laser.

A model system has been developed to quantitatively investigate bacteria-cell interaction using a rough mutant of Salmonella and human peripheral blood lymphocytes. The effect of lymphocyte irradiation by low-power continuous wave Helium-Neon laser has been investigated since laser therapy in wound and decoubitous ulcer healing could involve the lymphoid cell function. Helium-Neon laser irradiation is shown here to enhance the adherence of Salmonella to lymphocytes. In particular, changes in newly defined binding parameters show that laser irradiation increases the frequency of binding-lymphocytes, the affinity of Salmonella for lymphocytes and the number of lymphocyte receptor sites as well.