EXPRESSION OF ALPHA-FETOPROTEIN AND INTERLEUKIN-2 RECEPTORS AND IMPAIRMENT OF MEMBRANE FLUIDITY IN PERIPHERAL-BLOOD MONONUCLEAR-CELLS FROM AIDS AND RELATED SYNDROMES

We have previously shown that the expression of a-fetoprotein (AFP) re ceptors is impaired in mitogen-activated peripheral blood mononuclear cells (PBMCs) from HIV+ individuals and that this novel abnormality re flects an unusual proliferation response of PBMCs to mitogenic stimuli . Here we comparatively analyze, in PBMCs from patients with AIDS and related syndromes, (1) changes in membrane fluidity, measured as the c holesterol/phospholipid ratio (CH/PL), and (2) changes in the expressi on of AFP receptors and of the a chain of the IL-2 receptor (TAC antig en). Relative to normal cells, the expression of AFP and IL-2 receptor s appeared considerably reduced in AIDS-related complex (ARC) and AIDS patients. In asymptomatic HIV+ individuals the amount of AFP receptor s was within the normal range, whereas that of IL-2 receptors increase d twice. CWPL ratios were significantly lower in PHA-activated than in quiescent PBMCs from healthy donors, which implies a gain in membrane fluidity. For seropositive groups, no statistically significant chang es in CWPL ratios were appreciated on PHA activation, Nevertheless, in HIV+ asymptomatic individuals, the CWPL ratio of quiescent PBMCs rese mbled that of PHA-activated PBMCs from healthy donors, suggesting that quiescent PBMCs are in a partially activated or ''preactivated'' stat us. With the worsening of the disease, toward ARC and AIDS stages, how ever, quiescent PBMCs from these groups showed a considerable loss in membrane fluidity, evidenced by elevated values of the CH/PL ratio. Th is radical change strongly suggest a severe alteration of the lipid me tabolism in these cells. Thus, HIV infection impairs the fluidity of t he cell membrane and, because the latter influences a large number of cellular functions, it may contribute to the progress of the disease b y altering normal sequences of lymphocyte activation and blastic trans formation.