SALMONELLA-TYPHIMURIUM INDUCES EXPRESSION OF P-GLYCOPROTEIN (MULTIDRUG-RESISTANCE-1 GENE-PRODUCT) IN A PROMONOCYTIC CELL-LINE CHRONICALLY INFECTED WITH HUMAN-IMMUNODEFICIENCY-VIRUS TYPE

This investigation showed that phagocytosis of virulent Salmonella typhimurium by promonocytic leukemia cell line U1, which contains human immunodeficiency virus type 1 (HIV-1) provirus but produces minimal or no virus, and not by uninfected U937 cell line resulted in expression of a functional P glycoprotein. Anti-tumor necrosis factor-alpha (TNF alpha) monoclonal antibody failed to inhibit S. typhimurium-induced P glycoprotein expression. Furthermore, recombinant TNF alpha had no effect on the induction of P glycoprotein expression in U1 cells. These data demonstrate that phagocytosis of virulent S. typhimurium results in an induction of P glycoprotein in association with HIV-1 infection; however, TNF alpha does not appear to play a significant role. Thus, secondary microbial infection in HIV-1-positive persons may play a role in multidrug resistance against antiviral and other antimicrobial agents by an induction of P glycoprotein.