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 μg) every 2 weaks. 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.