Preferential expression of IL-2 receptor subunits on memory populations within CD4⁺ and CD8⁺ T cells.

Interleukin-2; Monoclonal antibodies; CD4 antigen; T cells; Cell physiology

Using anti-Tac and anti-Mik-β1 monoclonal antibodies to α and β subunits of the interleukin-2 receptor (IL-2R), respectively, a marked difference in expression of IL-2R subunits on blood CD4+ and CD8+ T cells was demonstrated between adults and newborns. In the adult blood, reciprocal expression of IL-2Rα and IL-2Rβ was observed in CD4+ and CD8+ T cells. Some CD4+ T cells expressing IL-2Rα were often detected, but IL=2Rβ+ CD4+ cells were very few. On the other hand, CD8+ T cells expressed significant IL-2Rβ but little IL-2Rα. In marked contrast to adult individuals, both CD4+ and CD8+ T cells from the newborns, which seemed to consist mainly of naive populations, showed only negligible expression of IL=2R subunits, it was found that IL-2R subunits appeared to be preferentially expressed on CD4 + and CD8+ T cells with memory phenotypes in the adult blood. Isolated memory (CD45RO+) CD4+ and CD8+ T cells, unlike naive (CD45RO-) ones, were able to proliferate in response to exogenous IL-2 as well as the recall antigen. The present results suggest that IL-2R subunits expressed on circulating T-cell subsets may play an important role in memory T-cell function. [ABSTRACT FROM AUTHOR]