COMPARATIVE-ANALYSIS OF SYNGENEIC AND ALLOGENEIC MIXED LYMPHOCYTE-REACTION OF NATURALLY ACTIVATED AND RESTING T-CELLS

'Naturally' activated (NA) or resting T lymphocytes obtained from the spleen of normal BALB/c mice were compared in their capacity to mount a syngeneic mixed lymphocyte reaction (SMLR). Both T-cell subsets were able to proliferate and secrete IL-3/GM-CSF in SMLR cultures. IL-2 was present in 'resting' T-cell SMLR supernatants, and barely detectable in NA T-cell SMLR supernatants. Both NA and 'resting' T-cell SMLRs were inhibited with anti-class II, anti-CD4, or anti-IL-2R MoAbs. NA T cells exhibited a background proliferative and secretory activity in the absence of syngeneic accessory cells. This autonomous activity was susceptible to anti-CD4, but poorly inhibited with anti-class II MoAbs. Both NA and 'resting' T lymphocytes displayed strong responsiveness to allogeneic stimuli. The analysis of the relative frequency of proliferating cells in the SMLR (BALB/c), or allo-MLR (B10, B10.A, B10.D2) from NA or 'resting' T cells indicated an enrichment for syngeneic rectivity among NA T lymphocytes. The meaning of these results for NA T-cell function and repertoire is discussed.