[Rat immunoreactivity in experimental modeling of acute autohemorrhagic bihemispheric stroke in the presence of staphylococcal infection].

Experimental studies were made of rat immunoreactivity in experimental modeling of acute hemorrhagic stroke in staphylococcal infection. Bactericidal activity and reserve bactericidal activity of neutrophils in NBT-test enhance while mid-molecular CIC level decreases because of phagocyte activation. ABA high titers in blood reflect activation of autoimmune processes. Splenic mass increased suggesting activation of proliferation of splenic lymphoid cells or enhanced migration of immature lymphoid cells from bone marrow to the spleen. Experimental animals had suppressed functional activity of main lymphoid cells populations in blast-transformation reaction which may affect the course of early recovery, promote activation of infectious bacterial process, autoaggression. The results of the studies can serve the basis for further investigations of immune mechanisms involved in development of hemorrhagic stroke in the presence of infectious process.

[Immunosuppressive effects of pathogenic gram-negative bacteria]. / Immunosupressivnoe deistvie patogennykh gramotritsatel'nykh bakterii.

The review deals with the Immunosuppressive effects of virulent gram-negative bacteria (Salmonella, Shigela, Pseudomonas aeruginosa), with the importance of these effects for the bacteria to survive in the infected body. The above bacteria affect the immunity system in a different way, yet have common features. They are characterized by the occurrence of endotoxin shock, by the suppression of the phagocytic system and cell-mediated immunity. A significant role in suppressing a cellular immune response is played by the lipopolysaccharide of virulent bacteria that greatly differs from that of nonvirulent strains. The immunosuppressive activity of the bacteria and their lipopolysaccharide is closely related to their virulent properties.

[Dependence of immunosuppressive action of lipopolysaccharide on degree of Salmonella pathogenicity]. / Zavisimost' immunosupessivnogo deistviia lipopolisakharida ot stepeni patogennosti sal'monell.

Immunosuppressive activity of Salmonella typhimurium extracellular lipopolysaccharide (LPS) was studied. In this study isogenic S. typhimurium strains with different degree of virulence were used. The attenuation of these strains was linked with mutations on their chromosome (altered synthesis of RNA polymerase or gyrase DNA) or their own virulence plasmid (the insertion of transposon Tn-5). To obtain LPS fraction with different molecular weights, the filtrate of bacterial culture was subjected to gel filtration through a column packed with Sephadex G-200. The immunosuppressive action of LPS fractions was determined on the model of delayed-type hypersensitivity to nonbacterial antigen in experiments on BALB/c mice. The study revealed that transposon-mediated mutation on plasmid, accompanied by the attenuation of salmonellae, led to the loss of immunosuppressive activity of the high-molecular heat-sensitive component of LPS; only the second heat-resistant component with medium molecular weight retained its activity. The presence of two chromosomal attenuating mutations (rifr nalr) was accompanied by the loss of immunosuppressive activity in both components of LPS.

[The immunosuppressive action of different fractions of Salmonella typhimurium lipopolysaccharide]. / Immunosupressiruiushchee deistvie razlichnykh fraktsii lipopolisakharida Salmonella typhimurium.

The suppressing activity of lipopolysaccharide (LPS) of the filtrates of genetically related S. typhimurium 415 and 415/307 cultures with respect to delayed hypersensitivity to nonbacterial antigen in mice was studied. In LPS of the virulent strain two immunosuppressing fractions differing in their molecular weight were detected by the method of gel filtration. One of them was detected in LPS of the genetically related nonplasmid clone of S. typhimurium 415/307. The possibility of the chemical inactivation and reactivation of the immunosuppressing properties of LPS was shown.

[Immunosuppressive components of extracellular lipopolysaccharide highly virulent strain Salmonella typhimurium 1468]. / Immunosupressivnye komponenty ékstratselliuliarnogo lipopolisakharida vysokovirulentnogo shtamma Salmonella typhimurium 1468.

Immunosuppressive activity of culture liquid substrate (CFS) of highly virulent strain Salmonella typhimurium has been studied. A model of delayed hypersensitivity (DHS) to nonbacterial antigen in mice, a method of gel-filtration through the sephadex column G-200, immunosorbents were used. Three components with immunosuppressive activity: thermolabile component and thermostable one with direct immunosuppressive action and the third thermolabile component which manifested inductive immunosuppressive activity only after redox treatment have been revealed in the strain CFS. O-specific and lipid parts were found in the composition of all the components. This allowed them to be related to lipopolysaccharide.

[The immunosuppressive activity of filtrates of the culture broth from nonvirulent salmonellae]. / Izuchenie immunosupressivnoi aktivnosti fil'tratov kul'tural'noi zhidkosti nevirulentnykh sal'monell.

Cultural filtrates (CF) of avirulent Salmonella virchow and Salmonella dublin have been studied for their influence on the delayed type hypersensitivity (DTH) to test-antigen in mice. It is found that i.p. injection of CF inhibits DTH in mice. The immunosuppressive activity is indicated in lipid fraction of CF and it may be removed from CF by the O-specific immunosorbent. It is heat-stable and disappears after phenol or trichloroacetic acid treatment. Gel filtration data evidence for high molecular weight of the active factor. These facts indicate to the connection of immunosuppressive activity with native lipopolysaccharide of avirulent Salmonella.