Effect of Bacillus Calmette-Guérin infection on delayed footpad reaction to Listeria monocytogenes

Effects of stimulated or immunologically activated macrophages on the induction of immune responses to Listeria monocytogenes

The influences of peritoneal macrophages induced by proteose peptone, Corynebacterium parvum (C. parvum) or Bacillus Calmette Guérin (BCG) on the initiation and development of immune responses and protection against Listeria monocytogenes infection were studied in mice. Mice treated intraperitoneally (i.p.) with proteose peptone 4 days previously showed much the same level of protection against an intraperitoneal infection with Listeria as untreated mice. Mice treated i.p. with C. parvum 4 days previously, of which peritoneal macrophages had increased abilities for intracellular killing of Listeria and O2- generation as compared with peptone-elicited macrophages, exhibited an enhanced resistance against the listerial infection. The degree of immune responses, as assessed by delayed footpad reaction (DFR), was rather depressed in these mice because C. parvum-activated macrophages acting as scavenger cells reduced the amount of effective antigenic stimulation. BCG-activated peritoneal macrophages from mice treated i.p. with BCG 14 days previously showed a strong ability for antigen presentation in correlation with increases in the number of Ia-bearing macrophages and in the level of interleukin 1 (IL 1) production. These mice showed an early appearance of DFR response and a markedly enhanced resistance against the listerial infection. These results suggested that the differences in macrophage activities as scavenger cells, cytokine-secreting cells and antigen presenting cells may account for the differences in the responsiveness against listerial infection in peptone-, C. parvum- and BCG-treated mice.

Augmentation of host defense against Listeria monocytogenes infection by oral administration with polysaccharide RBS (RON)

Protection against Listeria monocytogenes in mice was enhanced by oral administration with a 30 mg/kg/day dose of polysaccharide RBS for 10 days. In mice treated with RBS, an enhanced elimination in vivo of L. monocytogenes was observed at the relatively late phase of listerial infection in correlation with enhanced immune responses against L. monocytogenes. The peritoneal macrophages from mice treated with RBS exhibited an increased activity of accessory cells for immune responses as assessed by production of interleukin-1 and antigen presentation to Listeria-immune T-cells. An increased activity of macrophages acting as accessory cells for immune responses may play important roles in the enhanced resistance against L. monocytogenes in mice treated orally with RBS.

Protective effect of a traditional Chinese medicine, xiao-chai-hu-tang (Japanese name: shosaiko-to), on Listeria monocytogenes infection in mice

Lethal effect of Listeria monocytogenes (L. monocytogenes) in mice was prevented by an intraperitoneal (ip) injection of a traditional Chinese herbal medicine, xiao-chai-hu-tang (Japanese name: shosaiko-to), 4 days before ip bacterial infection. The numbers of bacteria in the peritoneal cavity and liver were smaller in shosaiko-to-treated mice from one day after the infection. Macrophage accumulation in the peritoneal cavity after ip inoculation of L. monocytogenes was observed in both untreated and shosaiko-to-treated mice. Although rates of such increases were almost the same between both groups, the absolute number of macrophages was larger in shosaiko-to-treated than in untreated mice because of a higher level of the macrophage number at 4 days after ip injection of shosaiko-to. In untreated mice, bactericidal activity of peritoneal macrophages decreased from one day to 3 days after ip injection of killed L. monocytogenes. Such an activity was maintained at the same level from 1 to 3 days in shosaiko-to-treated mice. Augmented accumulation of macrophages and maintenance of their bactericidal activity may be main mechanisms of the augmented resistance in shosaiko-to-treated mice. Augmented resistance against bacterial growth in the thigh muscle in ip shosaiko-to-treated mice may be caused by such mechanisms. The effect of shosaiko-to observed at an early stage of infection may be T cell-independent, since such an effect was observed in athymic nude mice and delayed footpad reaction could not be detected at such a timing in euthymic normal mice.

Simultaneous vaccination by three living attenuated strains of Brucella, Salmonella and Chlamydia in mice

Associations of vaccines for simultaneous administration were successfully developed long ago, in particular in human medicine, although there have been very few attempts to associate living bacterial vaccines. Unfortunately, living vaccines can interact with one another resulting in either a virulent infection or an exclusion of one by the other. Having developed two new low virulence vaccinal strains of Chlamydia psittaci var. ovis and Salmonella abortus ovis for use in veterinary medicine, we studied associations of both and with the Brucella melitensis Rev1 vaccine in mice. There was no interaction between the Chlamydia and the Salmonella vaccines and between the Salmonella and the Brucella vaccines from the point of view of immunogenicity. In contrast, anti-Chlamydia immunity was decreased by about 15-19% when the Chlamydia vaccine was associated with the Brucella vaccine in double or triple association. Surprisingly, the Chlamydia vaccinal strain infection was slightly extended when administered in association. The simultaneous vaccination we tested could be of great interest in veterinary medicine, but special attention must be devoted to anti-Chlamydia immunity and would have to be studied in a ewe model.