Conversion of Salmonella typhimurium to L-forms contributes to the maintenance of acquired immunity against murine typhoid.
Conversion of Salmonella typhimurium to L-forms, both in vitro and in vivo, resulted in the expression of proteins cross-reacting to the mycobacterial 65,000 MW heat-shock protein (hsp). Immunization of C3H/HeJ mice with a protective dose of stable L-form S. typhimurium induced gamma delta T cells in the liver, in accordance with the multiplication of L-form Salmonella in Kupffer cells. The number of gamma delta T cells decreased after the intracellular growth of L-form Salmonella plateaued. Persistance of the L-forms in Kupffer cells, however, allowed hepatic gamma delta T cells to increase within 48 hr of infection with virulent S. typhimurium. Thus, the intrahepatic colonization of L-form Salmonella seems to keep gamma delta T cells on standby, but the emergence of these T cells does not correlate with the expression of L-form hsp. In addition, Kupffer cells colonized by L-forms constitutively synthesized mRNA for interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha). These results suggest that conversion of S. typhimurium to L-forms in phagocytic cells builds up and maintains acquired resistance, conferred by live-cell vaccines of S. typhimurium, against murine typhoid.
D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins; D015153:Blotting, Western; D018834:Chaperonin 60; D018833:Chaperonins / Q000276:immunology; D005260:Female; D007114:Immunization; D007700:Kinetics; D007728:Kupffer Cells / Q000276:immunology; D007740:L Forms / Q000276:immunology*; D008099:Liver / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D016133:Polymerase Chain Reaction; D016692:Receptors, Antigen, T-Cell, gamma-delta; D012486:Salmonella typhimurium / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014435:Typhoid Fever / Q000276:immunology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D018834:Chaperonin 60; D016692:Receptors, Antigen, T-Cell, gamma-delta; C074119:heat-shock protein 65, Mycobacterium; D018833:Chaperonins