P-170 glycoprotein (P-170) is involved in the impairment of natural killer cell-mediated cytotoxicity in HIV+ patients.

In the present study we analyze peripheral blood lymphocytes (PBL) from patients with human immunodeficiency virus (HIV) infection for both phenotypic expression and function of P-glycoprotein (P-170). This transmembrane efflux pump is known to be one of the mechanisms responsible for the multidrug resistance (MDR) in cancer therapy and it is also constitutively expressed in normal PBL. P-170 function, evaluated as Rhodamine 123 (Rh123) efflux in flow cytometry, was found to be significantly reduced in CD16+ natural killer (NK) cells from patients with HIV infection. Interestingly, this reduced efflux significantly correlates with the decreased NK cytotoxicity observed in HIV+ patients, as evaluated against the NK-specific K562 target cell line. These results support a possible role of the P-170-related pump in specific immunological lymphocyte function such as NK cell-mediated cytotoxicity.