REDUCED CD4 CELL COUNTS IN BLOOD DO NOT REFLECT CD4 CELL DEPLETION INTONSILLAR TISSUE IN ASYMPTOMATIC HIV-1 INFECTION

Objective: To investigate whether the loss of CD4 cells seen in periph eral circulation of HIV-l-positive individuals reflects a similar depl etion of CD4 cells from lymphoid tissue. Design: CD4 and CD8 cells in tonsillar mononuclear cell suspensions were quantified relative to ton sillar B cells, as these were thought to remain numerically unchanged in the course of HIV infection. Results were related to the CD4 cell c ounts in blood and to the clinical status of the patients. Methods: Bl ood samples and tonsillar tissue were obtained from 13 HIV-1-seroposit ive individuals and six seronegative controls. B cells and T-cell subs ets in mononuclear cells were quantified using a three-colour flow cyt ometry protocol. Histological sections were morphologically classified and B-cell areas were quantified by morphometry. Results: The B-cell fraction was confirmed to be relatively unchanged in asymptomatic HIV- l-seropositive individuals compared with controls. The tonsillar CD4 : B-cell ratios in asymptomatic individuals was similar to those seen i n controls, whereas the CD4:B-cell ratios in symptomatic HIV-l-infecte d individuals were greatly reduced. The tonsillar CD4:CD8 cell ratios in HIV-l-infected individuals were much lower than those seen in contr ols, in the asymptomatic group due to a considerable expansion of the tonsillar CD8 cell subset, and in the symptomatic group also due to a loss of CD4 cells. Conclusions: We found no evidence of CD4 cell deple tion in tonsillar tissue in asymptomatic HIV-l-infected individuals de spite low CD4 cell counts in blood. Loss of CD4 cells from this lympho id tissue seems to occur as a late-stage phenomenon correlated with th e onset of clinical symptoms.