Sensitivity of bacteria to NO2 -/NO and to L-arginine-dependent system in murine macrophages was tested.

No abstract

The role of CD14 in the phagocytosis and killing of microorganisms was investigated using macrophage‐like cell lines, CD14‐positive J774.1 cells and CD14‐negative mutant J7.DEF3 cells derived from J744.1 cells. The cells were infected with Salmonella typhimurium organisms of the smooth (S)‐form LT2, mutant rough (R)‐form TV148 or Staphylococcus aureus 248βH. At 30 or 180 min incubation, the cells were washed and disrupted. Colony‐forming units (CFUs) liberated from the disrupted cells were determined by quantitative cultivation, and the phagocytic index and killing rate were calculated. Both the phagocytic index and killing rate of J774.1 cells against LT2 organisms were greater than those of J7.DEF.3 cells. However, the index and rate of J774.1 cells against TV148 and 248βH organisms were similar to those of the J7.DEF.3 cells. The phagocytosis of LT2 organisms by J774.1 cells was partially inhibited by S‐form LPS (S‐LPS) and anti‐CD14 antibody, but not by R‐chemotype LPS (R‐LPS). These results suggest that CD14 participates in the phagocytosis of S‐form Salmonella.

No abstract

Stimulation of resistance induced by muramyl dipeptide (MDP) and its analog, N-MDP-Nt-stearoyl-L-lysine [MDP-Lys(L18)J, was examined in experimental salmonellosis in CBA/N defective mice with X-linked immunodeficiency to virulent Salmonella enteritidis no. 11. An injection of either MDP or MDP-Lys(L18) did not induce any effective protection, but repeated injections of MDP-Lys(L18) (100 ,ug per mouse per day for 3 days consecutively) to the mice before bacterial challenge gave some protection. Multiple injections with MDPs once a day for several days consecutively strongly increased bactericidal capacity in the peritoneal cavities and spleens of the mice. Moreover, previous injection of the MDPs could elevate the phagocytic function of the reticuloendothelial system in the defective mice. These results indicate that nonspecific resistance of CBA/N defective mice to salmonella infection can be improved by previous administrations of MDPs.