Detection of circulating p24 antigen-positive CD4+ cells during HIV infection by flow cytometry.
OBJECTIVE
To determine the amount of circulating CD4+ cells positive for intracellular p24 antigen during HIV infection, and to correlate the results with clinical, virological and therapeutic parameters.


METHODS
Data were obtained from 24 anti-HIV-negative subjects (controls) and 47 anti-HIV-positive patients classified according to clinical diagnosis, serum p24-antigen assay results, and antiretroviral treatment with zidovudine, using a modified flow cytometric assay for the detection of intracellular HIV p24 antigen (p24-FCA) in circulating CD4+ lymphocytes.


RESULTS
The proportion of CD4+ lymphocytes positive for p24-FCA correlated well with HIV infection (1.685 +/- 1.902 versus 0.160 +/- 0.152 in controls; P < 0.001) and clinical progression [Centers for Disease Control (CDC) stage II: 1.310 +/- 1.187; CDC stage III 1.145 +/- 1.442; CDC stage IVA/C2: 2.335 +/- 2.112; CDC stage IVC1: 2.066 +/- 2.420]. The percentage of CD4+ cells positive for HIV p24-FCA was inversely correlated with an absolute peripheral blood CD4+ lymphocyte count (Spearman's rank correlation = -0.324; P < 0.05). However, there was no statistically significant difference between patients in presence (n = 27; 1.938 +/- 2.095) or absence (n = 20; 1.343 +/- 1.594) of serum p24 Ag. The variable linked most strongly to the detection of intracellular p24 in anti-HIV-positive patients was zidovudine treatment: the proportion of p24-FCA-positive CD4+ lymphocytes was significantly lower (0.825 +/- 0.910) in the treated patients (n = 25) than in the untreated patients (n = 22; 2.662 +/- 2.248; P < 0.001).


CONCLUSIONS
Our results suggest that CD4+ p24 Ag-FCA is a rapid and easy test for the identification of the proportion of CD4+ lymphocytes with intracellular p24 Ag, and that it could be more appropriate than serum p24 Ag assay in evaluating disease progression and efficacy of antiretroviral treatment.
Institute of Infectious Diseases, University of Bologna, Italy.
P
P
Costigliola
F
F
Tumietto
E
E
Ricchi
F
F
Chiodo
D001775:Blood Circulation; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry*; D005434:Flow Cytometry / Q000379:methods*; D016655:HIV Core Protein p24 / Q000276:immunology*; D015658:HIV Infections / Q000175:diagnosis* / Q000188:drug therapy; D006679:HIV Seropositivity / Q000175:diagnosis; D006801:Humans; D013997:Time Factors; D016896:Treatment Outcome; D015215:Zidovudine / Q000627:therapeutic use
D016655:HIV Core Protein p24; D015215:Zidovudine