Secretory Leukocyte Protease Inhibitor Inhibits Infection of Monocytes and Lymphocytes with Human Immunodeficiency Virus Type 1 but Does Not Interfere with Transcytosis of Cell-Associated Virus across Tight Epithelial Barriers

In the present study, we demonstrate that recombinant human secretory leukocyte protease inhibitor (rhSLPI) inhibits infection of lymphocyte- and monocyte-derived tumor cell lines and peripheral blood lymphocytes with laboratory-adapted isolates and with the primary isolate, NDK, of free human immunodeficiency virus type 1 (HIV-1). In contrast, rhSLPI did not exhibit inhibitory activity toward transcytosis of cell-associated HIV-1 through a tight monolayer of endometrial epithelial cells. These observations indicate that the inhibitory effect of SLPI is restricted to free HIV-1 in corporal fluids.