Influence of first-wave derived T lymphocytes in the long term functional reconstitution of allogeneic T cell deficient hosts.

The functional immunological reconstitution and the patterns of cytokine secretion were comparatively studied in BALB/c nu/nu mice grafted with allogeneic B6.Thy-1.1+ E14 or E18 embryonic thymus. In spite of equivalent proliferative responses to both mitogen or MLR stimuli, the two groups presented different cytokine patterns. B6 E18-thymus grafted BALB/c nu/nu mice showed a predominant IL-2/IFN-gamma secretion in response to mitogen or to CBA haplotype, with insignificant secretion of either cytokine to the tolerated BALB/c or donor B6 haplotype. In contrast, E14 grafted mice showed a significant IL-10 secretion, both in response to mitogens or to the tolerated haplotypes, even in the absence of a detectable proliferative response. A significant IFN-gamma secretion appeared only accompanying high responses to CBA. The preferential Th2 profile associated to the E14 chimeras was coincident with a longer lifespan of the nude host kept in a conventional environment, higher CD3+ cells frequency in the blood and functional restoration of allogeneic skin graft rejection, not seen on the E18 chimeras. The meaning of these results is discussed in relation to the previously described longer persistence of the first-wave donor derived lymphocytes in the allogeneic BALB/c periphery, also exclusive of the E14 grafted group.