Different characteristics of allogeneic and trinitrophenyl-modified H-2-restricted cell-mediated lympholysis: analysis of differences in interleukin-2 dependency using an ontogenical approach.

Ontogenical development of in vitro allogeneic cell-mediated lympholysis (CML) and in vitro trinitrophenyl (TNP)-modified CML was studied mainly in correlation with helper cell activity, using C3H/HeN and C57BL/6 mice. Allogeneic and TNP-modified CML were not detected in the spleen of these mice at 1 week after birth. Allogeneic CML was detectable, in parallel with increases in age. This activity in 5-week-old mice was much the same as in the 8-week-old mice but the TNP-modified CML did not appear until 8 weeks after birth. Exogenous interleukin-2 (IL-2) induced sufficient activity of TNP-modified CML, even in spleen cells from 1-week-old mice, while the same treatment had a weak but significant effect on the induction of allogeneic CML in these same cells. Experiments on the mixed lymphocyte reaction (MLR) in the presence of exogenous IL-2 showed that lymphocyte proliferation in response to TNP-modified cells was higher than that in response to allogeneic cells. These results suggest different dependencies on IL-2 between allogeneic and TNP-modified killer precursor cells. Endogenous IL-2 production and proliferative response in MLR showed that helper cells contributing to the TNP-modified CML matured later, compared to allogeneic CML. Different sensitivities to IL-2 in two types of CML, in addition to different ontogenical developments, suggest that cytotoxic T lymphocytes to allogeneic cells differ quantitatively and qualitatively from TNP-modified H-2-restricted killer cells.