Confocal microscopy assessment of lymphoid tissues with follicular hyperplasia from patients infected with human immunodeficiency virus type 1.

ABSTRACT

OBJECTIVE: To characterize human immunodeficiency virus (HIV) infection of lymphoid tissues during follicular hyperplasia. METHODS: We examined 10 tonsil/adenoid, 3 parotid lymphoepithelial cyst, and 7 lymph node specimens that had been surgically removed from 13 patients infected with HIV-1. Characteristics of productive HIV-1 infection were assessed using immunocytochemistry for HIV-1 p24. Cellular colocalization was determined with the aid of a confocal microscope using double immunofluorescent staining for HIV-1 p24 and cell-specific markers. RESULTS: All specimens showed follicular hyperplasia. Using confocal microscopy with three-dimensional reconstruction, HIV-1 p24 was seen to be "intimately" colocalized with CD21 within the germinal centers. While lymphoid follicles were generally hyperplastic, only a subset of these follicles contained HIV-1 p24. Occasional HIV-1-expressing mononuclear cells identified outside follicles stained for CD68 or CD3. CONCLUSIONS: The differential involvement of hyperplastic follicles by HIV-1 within individual lymphoid tissues and the intimate colocalization of HIV-1 p24 and CD21 suggest that infected follicular dendritic cells may be an important reservoir of HIV-1 during follicular hyperplasia.