The use of the full blood count and differential parameters to assess immune activation levels in asymptomatic, untreated HIV infection.

BACKGROUND: A feature of HIV/AIDS is chronic immune activation, which results in a number of complications including inflammation-related disorders and blood cytopaenias. Immune activation status is not routinely tested in HIV infection. However, the full blood count (FBC) is a commonly performed test. OBJECTIVE: We hypothesised that FBC parameters would be significantly different in HIV-infected v. -uninfected individuals, and that some of these parameters would correlate with markers of immune activation (i.e. percentage CD38 expression on CD8(+) T cells (%CD38onCD8)) and disease progression (i.e. CD4(+) counts) in HIV infection. METHODS: This was a cross-sectional study with 83 HIV-infected adults who were antiretroviral therapy-naive and clinically well, and 51 HIV-uninfected adults. The %CD38onCD8 and CD4(+) counts were determined by flow cytometry and the FBC was performed on a Siemens ADVIA 2120 system. FBC parameters investigated were total white cell count (WCC), haemoglobin (Hb) concentration, platelet count, absolute neutrophil count, absolute lymphocyte count, and percentage of large unstained cells (%LUCs). RESULTS: Significant differences were found between the HIV-infected and -uninfected groups for total WCC, Hb, neutrophil count, lymphocyte count and %LUCs. The mean ± standard deviation (SD) for the total WCC (5.3±1.3 v. 6.9±2.2; p≤0.001) and the %LUCs (2.5±0.9 v. 2.0±0.9; p=0.001) both showed correlations with CD4(+) counts and %CD38onCD8. CONCLUSION: The total WCC and %LUCs showed significant differences in HIV-infected individuals and correlated with markers of immune activation and disease progression. This suggests the potential use of these parameters as markers of immune activation in HIV infection.