CONFOCAL MICROSCOPY ASSESSMENT OF LYMPHOID-TISSUES WITH FOLLICULAR HYPERPLASIA FROM PATIENTS INFECTED WITH HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

Objective.-To characterize human immunodeficiency virus (HIV) infectio n of lymphoid tissues during follicular hyperplasia. Methods.-We exami ned 10 tonsil/adenoid, 3 parotid lymphoepithelial cyst, and 7 lymph no de specimens that had been surgically removed from 13 patients infecte d with HIV-1. Characteristics of productive HIV-1 infection were asses sed using immunocytochemistry for HIV-1 p24. Cellular colocalization w as determined with the aid of a confocal microscope using double immun ofluorescent staining for HIV-1 p24 and cell-specific markers. Results .-All specimens showed follicular hyperplasia. Using confocal microsco py with three-dimensional reconstruction, HIV-1 p24 was seen to be ''i ntimately'' colocalized with CD21 within the germinal centers. While l ymphoid 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. Conclusio ns.-The differential involvement of hyperplastic follicles by HIV-1 wi thin individual lymphoid tissues and the intimate colocalization of HI V-1 p24 and CD21 suggest that infected follicular dendritic cells may be an important reservoir of HIV-1 during follicular hyperplasia.