CHANGES IN EXPRESSION OF CD45R DURING THE DEVELOPMENT OF TH1 AND TH2 CELL-LINES

Previous studies using anti-CD45R monoclonal antibodies (mAb) have shown that normal CD4+ T cells can be separated into virgin and memory cells based on their level of expression of CD45R. CD45R(hi) (Virgin) Tcells secrete interleukin (IL)-2 whereas CD45R(lo) (memory) T cells secrete both IL-2 and IL-4. In contrast to these results, studies using cultured T cell lines have shown that IL-2-secreting T helper cell type 1 (T(h)1) cells are CD45R(lo) and IL-4-secreting T(h)2 cells are CD45R(hi). To resolve this discrepancy, and to determine how the T(h)1 and T(h)2 cell lines relate to memory CD45R(lo) and virgin CD45R(hi) CD4+ T cells, we have isolated CD45R(lo) cells from alloantigen-primed mice and developed allospecific T(h)1 and T(h)2 cell lines. The lymphokines secreted by these lines were then evaluated. Our results show that as CD45R(lo) Tcells develop into in vitro cell lines which secrete IL-4, they become CD45R(hi). In contrast, CD45R(lo) cells that develop into lines which secrete IL-2 maintain their CD45R(lo) phenotype. Thus, although both T(h)1 and T(h)2 cells arise initially from CD45R(lo) cells, T(h)2 cells become CD45R(hi) during prolonged in vitro culture but, T(h)1 cells do not.