Cellular immunity

CYTOPATHOGENIC EFFECT OF BRUCELLA SPHEROPLASTS ON MONOCYTES IN TISSUE CULTURE

Freeman, Bob A. (The University of Chicago, Chicago, Ill.), and Barry H. Rumack. Cytopathogenic effect of Brucella spheroplasts on monocytes in tissue culture. J. Bacteriol. 88:1310-1315. 1964.-Mononuclear phagocytes from guinea pig peritoneal exudates were shown to ingest both normal Brucella suis and spheroplasts prepared from B. suis by treatment with glycine and with penicillin. Quantitative ingestion studies with P(32)-labeled Brucella showed that rough normal Brucella are ingested at a greater rate than are smooth normal Brucella. Spheroplasts prepared from smooth cells were phagocytized at a greater rate than were the normal smooth cells, and spheroplasts prepared from rough Brucella were phagocytized well, although apparently to a lesser extent than from the normal rough Brucella. The degree of phagocytosis of all spheroplasts appeared to reach a peak and then decrease, indicating a release of ingested bacteria; this release of intracellular bacteria is believed to be due to the cytopathogenic effect exerted by the spheroplasts. Direct microscopic observations showed that infection with living spheroplasts prepared from either smooth or rough Brucella destroyed a major portion of the host cells within 4 hr, but that formalin-killed spheroplasts were no more destructive than were normal Brucella. When host cell destruction was assayed by the release of cellular constituents into the medium, it was apparent that host-cell destruction by spheroplasts reaches a significant level within 0.5 hr after ingestion begins, and is almost complete by 4 hr. The implications of these findings in studies on the nature of intracellular Brucella are discussed.

UTILIZATION OF EXTERNAL GROWTH FACTORS BY INTRACELLULAR MICROBES: MYCOBACTERIUM PARATUBERCULOSIS AND WOOD PIGEON MYCOBACTERIA

Wheeler, William C. (Johns Hopkins University-Leonard Wood Memorial Leprosy Research Laboratory, Baltimore, Md.), and John H. Hanks. Utilization of external growth factors by intracellular microbes: Mycobacterium paratuberculosis and wood pigeon mycobacteria. J. Bacteriol. 89:889-896. 1965.-The extent to which the intracellular growth of microbes is dependent upon capacities for growth in vitro has been investigated by use of organisms which require a specific factor, mycobactin, for isolation and growth on conventional mycobacterial media. Similarities between growth on bacteriological media and within tissue cells have been demonstrated by examining the responses of Mycobacterium paratuberculosis and wood pigeon mycobacteria to mycobactin, iron, CO(2), and glycerol, and to the low pH which characterizes phagocytic vacuoles. The results indicate that success of intracellular infections depends upon the independent growth of microbes and that the phagocytic vacuoles of sheep and mouse macrophages seem to be freely accessible to bacterial growth factors, minerals, and substrates. Because these factors did not modify the appearance, overall metabolism, or surface properties of macrophages, it was concluded that the intracellular growth of microbes is not determined solely by the components, metabolism, or immunological properties of host cells, but is influenced to an important degree by compounds and conditions provided by extracellular environments.

Immunity to Salmonella infection

The foregoing literature review and data presentation have been set forth in the hope of clarifying some complex and confusing issues in regard to Salmonella infection. From a practical point of view, the information presented has implications for the direction to take with regard to improving the current typhoid vaccine, as the presently used acetone-killed cell preparation has considerable toxicity. The issues are important from a theoretical standpoint, because they have bearing on the nature of the concepts researchers and clinicians carry as working hypothesis with regard to the mechanisms of immunity to Salmonella infection. An incomplete appreciation of the literature seems to have led many scientists to believe that only cellular immunity can protect a mouse, and by analogy a human, against Salmonella. The logical deduction from such a premise is that only live vaccines will be effective in humans againsT S. typhi. Such a conclusion would appear unfounded, as documented in this review, for killed vaccines have been shown to be highly effective in vaccinating many mouse strains, as well as humans, against enteric fever.

Inability of spleen cells from chancre-immune rabbits to confer immunity to challenge with Treponema pallidum

Although several lines of evidence suggest that cellular immune mechanisms play a role in controlling infection due to Treponema pallidum, recent studies have shown that induction of acquired cellular resistance by antigenically unrelated organisms fails to protect rabbits against syphilitic infection, thereby casting doubt on this hypothesis. In the present paper we describe attempts to transfer immunity to syphilis by using spleen cells from chancre-immune rabbits. Intravenous infusion of 2 X 10(8) spleen lymphocytes was capable of transferring acquired cellular resistance to Listeria and delayed hypersensitivity to tuberculin. However, in eight separate experiments using outbred or inbred rabbits, 2 X 10(8) spleen cells from syphilis-immune animals failed to confer resistance to T. pallidum whether by intravenous or intradermal challenge. Mixing immune lymphocytes with treponemes immediately before intradermal inoculation also failed to confer resistance. Despite the fact that syphilitic infection stimulates cellular immune mechanisms and induces acquired cellular resistance to antigenically unrelated organisms, cellular immunity may not play an important role in immunity to syphilis.

Fractionation of Phenol Extracts from Brucella suis : Separation of Multiple Biologically Active Components

Brucella suis endotoxin prepared by a modification of Westphal's method was purified further by gel filtration and ion-exchange chromatography. The latter proved to be the most effective means of separating antigenic components associated with this fraction. All of the toxic activity was located in a single peak from carboxymethyl-Sephadex. Subsequent separation of this material on diethylaminoethyl (DEAE)-Sephadex indicated the presence of two or more toxic components in phenol extracts of B. suis . A factor which increases vascular permeability was separated by use of the ion exchanger DEAE-Sephadex, and was associated with the first peak. Its manifestations could be destroyed by heating at 60 C for 30 min or neutralized by reaction with specific antiserum. This permeability factor is believed to be distinct from other toxins which appear in column eluates and which can be assayed by skin induration.

Serum-mediated immune cellular responses to Brucella melitensis. I. Role of a macrophage-stimulating factor in promoting ingestion of Brucella by streptomycin-protected cells

Injection of rabbits with living Brucella melitensis Rev I induced the appearance of a macrophage-stimulating-factor (MSF) in the sera of these animals. MSF was involved in ingestion of bacilli, hastening the formation of protected loci as measured by the addition of lethal amounts of dihydrostreptomycin. When sufficient time had been allowed for effective ingestion, streptomycin had little effect. This in turn allowed for multiplication of bacilli intracellularly in the presence of 5 to 250 mug of drug per ml. MSF mediated more effective ingestion by both immune and normal macrophages. Under such conditions, there was little, if any, intracellular growth restriction by macrophages from immune animals. The activity appeared within the first 5 days after injection with 10(9) organisms and was present for several months. Three weeks after injection, the activity of serum was partially heat-labile. All activity was removed by absorption with heat-killed or living Rev I cells, suggesting that a specific globulin is concerned.

Cellular hypersensitivity and cellular immunity in the pathogensis of tuberculosis: specificity, systemic and local nature, and associated macrophage enzymes

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Opsonizing and bactericidal activity of antibodies against common antigen of Enterobacteriaceae

Domingue, Gerald J. (State University of New York at Buffalo, Buffalo, N.Y.), and Erwin Neter. Opsonizing and bactericidal activity of antibodies against common antigen of Enterobacteriaceae. J. Bacteriol. 91:129-133. 1966.-In addition to the well-known O, H, K, and Vi antigens, Enterobacteriaceae produce a common antigen, which was first identified by hemagglutination tests with Escherichia coli O14 antiserum. Studies on the biological significance of this antigen by in vitro phagocytic experiments have revealed that opsonization is markedly enhanced in the presence of the corresponding antibody, rabbit polymorphonuclear leukocytes, and normal rabbit serum. This effect is specific, because Pseudomonas aeruginosa, which is devoid of this antigen, is not opsonized under these conditions, and removal of the antibody by absorption markedly reduces the uptake of enteric bacteria containing the antigen. Opsonization thus represents another method for the study of this antigen-antibody system. Bactericidal tests have revealed that antibodies against this antigen, engendered in rabbits by different strains of enteric bacteria and various procedures, are bactericidal for E. coli O14 but not for other enteric bacteria, possibly due to previously demonstrated differences between the antigen moieties obtained from these microorganisms.

Studies on the mechanism of non-specific resistance to Brucella induced in mice by vaccination with BCG

Mice vaccinated with living or killed BCG become resistant to infection with Brucella abortus, as evidenced by a lower bacterial count in the spleen and liver as compared to controls. Some of the observed resistance is attributed to the ability of the treated mice to mobilize quickly a large number of macrophages in the abdominal cavity, since these macrophages could phagocytose and subsequently kill a proportion of the injected bacteria. However, the main antibacterial effect appears to take place in the spleen and liver. These organs contained most of the Brucellae found in the animal at 6 hours after challenge and showed the most significant differences between vaccinated and non-vaccinated animals.

Sera of BCG-treated mice contain a factor capable of conferring to normal animals some protection against challenge with Brucella.