Antigenic Modification, Rosette-Forming Cells, and Salmonella typhimurium Resistance in Outbred and Inbred Mice

Abstract

To assess the separate contributions of host T cells and the physical state of the antigen in the development of effective Salmonella resistance, glutaraldehyde-treated and untreated proteinand ribonucleic acid-rich extracts (E-RNA extracts) of virulent Salmonella typhimurium SR-li or attenuated S. typhimurium RIA were used to immunize Salmonella-resistant and Salmonella-susceptible strains of mice for the purpose of determining whether antigen-specific Tcell or B-cell responses were formed and, if so, which responses predominated. The resistance imparted to each mouse strain after vaccination with S. typhimurium RIA was used as the standard for comparison. The inbred mouse strains C57BL/6 and DBA/2 and their F1 hybrid (strain BDF1), outbred ICR Swiss mice, and endotoxin-resistant C3H/HeJ mice were examined for the capacity to develop resistance to lethal Salmonella infections, as well as the ability to generate antigen-reactive T cells. Only the BDF1, C3H/HeJ, and ICR Swiss mice were able to develop resistance to challenge infections mediated by the virulent SR-11 strain of S. typhimurium after vaccination with the living, attenuated RIA strain of S. typhimurium or immunization with E-RNA extracts. We developed an assay to identify the antigen-reactive rosette-forming lymphocytes present in lymph nodes and spleens of immunized mice. Levels of 0.2% or higher of theta antigenbearing, antigen-reactive rosette-forming cells were found in the lymph nodes or spleens or both of only the BDF1, C3H/HeJ, and ICR Swiss mice (i.e., in the "Salmonella responder" strains). Mouse strains C57BL/6 and DBA/2, which failed to develop resistance to lethal infections after immunization with the S. typhimurium RIA vaccine or with the E-RNA extracts, lacked effective numbers of antitheta antigen-sensitive rosette-forming cells. Modification of the effective E-RNA extracts by polymerization with glutaraldehyde resulted in a marked diminution in their abilities to induce resistance to salmonellosis in the two responder mouse strains tested (BDF1 and ICR Swiss), even though detectable levels of antibody were induced.

In vitro effect of murine-derived transfer factor on Salmonella-specific rosette formation

“…In a recent study we demonstrated that the splenic lymphocytes of S. typhimurium-immune mice will form antigen-specific rosettes with coated SRBC (3). The majority of these RFL were found to be sensitive to antithymocyte serum plus complement.…”

“…Antigen-specific rosette formation assay. The procedure used to detect Salmonella-specific RFL was essentially that of Bigley et al (3). Briefly, to a 10-by 75-mm culture tube was added 0.1 ml of splenic lymphocytes (108/ml) and 0.2 ml of a 1% suspension of antigen-coated (Salmonella or Listeria) or normal SRBC.…”

“…The specificity of this serum for murine T cells was previously demonstrated (3). The procedure used to selectively eliminate T lymphocytes with antithymocyte serum plus guinea pig complement was essentially that of Bigley et al (3). Briefly, 108 splenic lymphocytes per ml were incubated for 30 min in a 37°C water bath with an equal volume of a 1:10 dilution of the antithymocyte serum.…”

Transfer of Salmonella resistance and delayed hypersensitivity with murine-derived transfer factor

“…The C3H/HeJ strain of mice is resistant to the lethal and adjuvant effects of endotoxin (6,22). Although these mice are very susceptible to the lethal effects of a challenge infection with S. typhimurium (LD50 < 10 bacteria), they can be protected from a lethal challenge infection after vaccination with the avirulent RIA strain of S. typhimurium (1). Both host protection to challenge infection and footpad swelling responses (DH) were demonstrated in these mice after receipt of TF prepared from the spleens of immune ICR Swiss mice.…”