Subset-specific expression of potassium channels in developing murine T lymphocytes.

Ion channels were studied in four major subsets of developing murine thymocytes by using patch-clamp recording and cell-surface staining techniques. The expression of three types of voltage-gated potassium channels in thymocytes varies consistently with the cell's developmental state and functional class as defined by cell-surface markers. One class of potassium channel (type n) predominates in immature thymocyte subsets as well as in mature-phenotype CD4+CD8- thymocytes (precursors to helper T lymphocytes), and the average surface density of this channel type correlates with the extent of cell proliferation. Two additional types of potassium channels (types n' and l) are found in the mature CD4-CD8+ thymocyte subset that contains precursors to cytotoxic and suppressor T cells. The subset-specific expression of type n' and l potassium channels suggests their use as additional cell-surface markers with which to identify precursors to the cytotoxic suppressor T cell lineage.