CD4-MLS REACTIVE T-CELLS ARE INDUCED IN MESENTERIC LYMPH-NODES OF SALMONELLA-ENTERITIDIS-INFECTED MICE( CD8+ CELLS LACKING SELF)

The percentage of mesenteric lymph node (MLN) cells that co-expressed both CD4 and CD8 was found to be from 5 to 7% in BALB/c and AKR/N mice bred under conventional conditions. In mice maintained under specific pathogen-free (SPF) conditions, the percentage fell below 2%. When mi ce were infected with an attenuated strain of Salmonella enteritidis ( SER), the percentage of CD4+CD8+ cells in MLN rose to 20-30% transient ly. In these mice, the total cell number and the percentage of CD8+ ce lls were not changed, but the CD4+ cell percentage was decreased. The expression intensity of TCR-alphabeta on CD4+CD8+ cells in the infecte d mice was higher in the MLN than in the thymus, but was similar to th at of mature peripheral T cells. Among the CD4+CD8+ cell population in MLN, TCR-Vbeta3+ cells were deleted but Vbeta6+ cells were present in BALB/c mice which possess endogenous superantigen Mls-2a, but lack Ml s-1a. In AKR mice with the inverse of the occurrence of the superantig ens, TCR-Vbeta3+ cells were present and Vbeta6+ cells were absent. The se data suggest that CD4+CD8+ cells in the MLN of SER-infected mice ma y belong to thymus-derived mature T cells undergoing negative selectio n and that they may appear following exogenous stimulation.