A video densitometric analysis of viral burden and follicular dendritic cell damage in lymph nodes in the latency phase of HIV infection

BACKGROUND: The aim of this study was to collect quantitative data on damage to follicular dendritic cells (FDC) and on the structure of germinal centers (GC) in the early phase of HIV infection. METHODS: Lymph node sections from 10 HIV(+) subjects and from 5 HIV(-) control subjects were stained by immunohistochemistry for CD21, an FDC marker; gp24, to assess the HIV load; and IgM, to measure antibodies within the GC. RESULTS: The volume fraction (V(area)) and the logarithm of the inverse gray value (ArLIGV) of CD21 areas showed a highly significant decrease in HIV(+) specimens. The mean ArLIGV values ranged between 0.0916 +/- 0.01 and 0.3826 +/- 0.11 versus 0.6856 +/- 0.19 on average in controls (P < 0.001 for both). Six of 10 HIV(+) specimens were positive for gp24. Staining was limited to GC and showed a distribution pattern similar to that of CD21. CONCLUSIONS: FDC already undergo considerable damage during the latency phase of HIV infection. The pattern of CD21 indicates that, although FDC decrease in number, the staining intensity of positive cells is basically preserved. Video densitometric analysis, an approach requiring a strict standardized protocol, may help monitor disease course and evaluate response to therapy by quantifying viral burden and lymph node damage.