Development, function and maintenance of T lymphocyte populations in P-glycoprotein-deficient mice

P-glycoproteins (P-gp) are widely known for their ability to pump drugs out of multidrug-resistant tumor cells, but are also normally expressed in a variety of nonmalignant tissues in mammals. In particular, lymphocytes and other hematopoietic cell lineages express P-gps during development and upon maturation in the periphery. However, the physiological significance of their expression in lymphocytes has been difficult to establish directly, although putative roles in cytotoxic function and cytokine release have previously been suggested. Progress toward resolving the actual nature of P-gp action in vivo has lately been aided by the production of P-gp-deficient mouse lines. Recent studies using these animals and data presented here indicate that P-gps are not required by peripheral T-lymphocytes for development or effector functions, but suggest they may have a role in the establishment or maintenance of certain T-cell population balances in the gut.