Plasma platelet-activating factor acetylhydrolase activity in human immunodeficiency virus infection and the acquired immunodeficiency syndrome

Platelet-activating factor (PAF) acetylhydrolase (PAF-AH) catalyzes the hyd rolysis of PAF, a mediator of inflammation, as well as other biologically a ctive oxidized phospholipids. In humans, plasma PAF-AH activity is bound to low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Higher l evels of plasma PAF-AH activity have been found in a variety of diseases, a nd are thought to be a defense mechanism against the toxic effects of PAF a nd oxidized phospholipids. We studied plasma PAF-AH activity in patients wi th human immunodeficiency virus (HIV) infection and acquired immunodeficien cy syndrome (AIDS), a disease characterized by chronic HIV infection and a systemic host response. Plasma PAF-AH activity was significantly greater in AIDS patients compared with control subjects (25.2 +/- 2.0 v17.0 +/- 0.8 n mol/min/ml, P <.001). The higher levels of plasma PAF-AH activity were foun d in LDL(28.2 +/- 2.2 v 18.3 +/- 1.0 nmol/min/ml for AIDS v controls, respe ctively P =.0005), but not in HDL. Plasma PAF-AH activity in AIDS correlate d with circulating interferon alfa (r =.575, P=.005) and plasma triglycerid es (r=.556, P <.0025). The presence of secondary infection in AIDS did not significantly change plasma PAF-AH activity. The initiation of a new antire troviral regimen with either a protease inhibitor or the nucleoside analog lamivudine did not significantly decrease plasma PAF-AH activity, despite s uccessful suppression of HIV RNA levels. Plasma PAF-AH activity may be a se nsitive marker of the host response to infection, and the higher levels of plasma and LDL-associated PAF-AH activity in patients with HIV infection an d AIDS may be a physiological response to protect the host against oxidativ e injury from PAF and oxidized phospholipids. Copyright (C) 1999 by W.B. Sa unders Company.