title: Changes in blood cell membrane properties in HIV type-1-infected patients.
abstract: To evaluate the possible HIV-1 infection-induced changes in cell membrane properties and in calcium signaling, membrane fluidity, acetylcholinesterase (AChE, a glycosylphosphatidylinositol-anchored protein) activity, and intracellular calcium concentration ([Ca2(+)](int)) were evaluated in lymphocytes and erythrocytes of infected individuals, previous to their engagement in antiretroviral therapy. Membrane fluidity was assessed by fluorescence spectroscopy measurements, using the fluorescence probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-[4-(trimethylamino)-phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH). AChE activity was determined by the colorimetric Ellman's method and [Ca2(+)](int) using the fluorescent fura-2 acetoxymethyl ester. When compared with the control group, lymphocytes of infected patients presented significantly decreased membrane fluidity, decreased AChE activity, and increased [Ca2(+)](int). Erythrocytes from HIV-infected patients presented decreased [Ca2(+)](int) when compared with the control group and decreased membrane fluidity near the lipid/water interface. Our data show that HIV-1 infection leads to biochemical and biophysical changes in the membrane itself and in membrane protein activity in lymphocytes (average of infected and noninfected subpopulations) and even in erythrocytes. The present observations are in agreement with a process of facilitated propagation of the infection to new cells, stimulation of virion production, and maintenance of a reservoir of erythrocyte-bound infectious virus.
authors.affiliation: Instituto de Biopatologia Química/Faculdade de Medicina de Lisboa and Unidade de Biopatologia Vascular/Instituto de Medicina Molecular, 1649-028 Lisboa, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Martins-Silva
authors.forename: Nuno C
authors.initials: NC
authors.lastname: Santos
authors.forename: M
authors.initials: M
authors.lastname: Doroana
authors.forename: N
authors.initials: N
authors.lastname: Duarte
authors.forename: L
authors.initials: L
authors.lastname: Tavares
authors.forename: F
authors.initials: F
authors.lastname: Antunes
authors.forename: Carlota
authors.initials: C
authors.lastname: Saldanha
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000328:Adult; D001772:Blood Cell Count; D002118:Calcium / Q000032:analysis*; D020013:Calcium Signaling; D004910:Erythrocyte Membrane / Q000378:metabolism* / Q000821:virology; D005260:Female; D015658:HIV Infections / Q000097:blood*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology; D008297:Male; D008560:Membrane Fluidity; D013223:Statistics as Topic; D019562:Viral Load
chemical_list: D000110:Acetylcholinesterase; D002118:Calcium