A significant percentage of normal T lymphocytes express HLA‐DP in the peripheral blood

Abstract
HLA-DP expression has been widely investigated on T lymphocytes activated under different conditions. In the present study, a double staining procedure was used in flow cytometric experiments to define DP expression on normal peripheral blood T lymphocytes. In about two-thirds of the case analyzed, DP was expressed on a higher percentage of normal peripheral T lymphocytes than DR was. This was particularly true for 1 of the 16 cases investigated in which the percentage of T lymphocytes expressing DP was 46% and in which DP expression was mainly the prerogative of CD8+ and CD56+ lymphocytes.