Molecular pathologic analysis of the tonsil in HTLV-I-infected individuals

Little is known about the role of the tonsils in HTLV-I infection. We perfo rmed molecular pathologic studies of tonsils in individuals positive or neg ative for anti-HTLV-I antibodies (HTLV-I-Ab) to clarify histologic characte ristics of tonsils in HTLV-I infection. We collected tonsils and peripheral blood samples from patients who underwent tonsillectomy in a prospective m anner. HTLV-I-Ab in serum was examined and presence of HTLV-I provirus was detected by polymerase chain reaction (PCR) in extracted DNA of both periph eral blood and tonsils. Histopathologic and immunohistochemical evaluations of tonsils were performed. HTLV-I seropositivity and PCR detection of HTLV -I provirus matched perfectly. Tonsil samples from seropositive individuals showed atrophy of the mantle zone and high numbers of T cells in the margi nal zone compared with findings in HTLV-I-negative samples. HTLV-I provirus could be detected only from extracted DNA of extrafollicular areas. PCR in situ hybridization also showed positive signals in some mononuclear cells located in the marginal zone. There was a significant correlation between H TLV-I proviral load in tonsils and in peripheral blood. These results sugge st the presence of characteristic histologic changes and deviated localizat ion of HTLV-I-infected cells in the tonsils of individuals positive for HTL V-I.