Interleukin 4 induces CD8 alpha expression on T cell receptor V gamma 5 thymocytes.

It is generally accepted that most T cell receptor (TcR) gamma/delta cells are CD4-CD8-. After in vitro culture; however, a low percentage of these cells express the CD8 alpha subunit. We show here that addition of recombinant interleukin (IL) 4 to IL 2-cultured murine TcR V gamma 5 thymocytes induces the expression of CD8 alpha; CD8 beta is not expressed. Co-addition of the anti-IL 4 mAb 11B11 abrogates the induction of CD8 alpha expression, ruling out the possibility of a contaminant. Furthermore, we demonstrate that a substantial part of freshly prepared TcR V gamma 5 thymocytes express CD8 alpha.