Can thymic epithelial cells be infected by human T-lymphotropic virus type 1?

The human T-lymphotropic virus type-1 (HTLV-1) is the cause of adult T cell leukaemias/lymphoma. Because thymic epithelial cells (TEC) express recently defined receptors for the virus, it seemed conceivable that these cells might be a target for HTLV-1 infection. We developed an in vitro co-culture system comprising HTLV-1+-infected T cells and human TECs. Infected T cells did adhere to TECs and, after 24 h, the viral proteins gp46 and p19 were observed in TECs. After incubating TECs with culture supernatants from HTLV-1+-infected T cells, we detected gp46 on TEC membranes and the HTLV-1 tax gene integrated in the TEC genome. In conclusion, the human thymic epithelium can be infected in vitro by HTLV-1, not only via cell-cell contact, but also via exposure to virus-containing medium.

Severe Chronic Active EBV Infection in an Adult Patient: Case Report

Severe chronic active Epstein-Barr virus (EBV) infection is a rare and life-threatening illness. Although the criteria for diagnosis include chronic or recurrent infectious mononucleosis-like symptoms lasting more than 6 months and high titers of anti-EBV antibodies, clinical and laboratory findings may be heterogeneous and flexible application of those criteria is necessary in cases showing typical clinical and pathologic findings. We report a case of severe chronic active EBV infection in a 62-yr-old female patient who showed classical clinical findings with infiltration of EBV-infected T lymphocytes in the bone marrow, spleen, and lymph nodes, and died four months after presentation.

Adult T cell leukemia/lymphoma with lymphopenia in a Korean

We experienced a case of adult T cell leukemia/lymphoma (ATLL) in a 48-year-old Korean female, who has never been abroad since birth and no history of blood transfusion. The patient had hypercalcemia and multiple lymphadenopathy. Histopathologic study of left cervical lymph node (LN) and bone marrow (BM) revealed that infiltrates of malignant lymphoid cells were composed of small, medium and large cells with pleomorphic nuclei. Smears of peripheral blood (PB) showed lymphopenia (16%) with the appearance of a few atypical lymphoid cells (less than 2%), but not the typical clover leaf cells seen in ATLL. Immunophenotypic study of LN and BM revealed T cell phenotype. PB showed increased CD4+ T cell (T(H), CD3/CD4+, 57%) and decreased CD8+ T cell counts (T(S), CD3/CD8+, 6.7%). The sera of the patient and her family were reactive for HTLV-I antibody. The specific sequences of pol, env, and tax of HTLV-I DNA were detected in the lymphoma cells and peripheral blood mononuclear cells (PBMC) using polymerase chain reaction. Ultrastructural examination of PBMC confirmed numerous type c virus particles in extracellular space. This case was an acute type of ATLL without overt leukemic features in PB. Despite chemotherapy and intensive conservative treatment, she died 3 months after admission.

Mecanismos de ativaçäo do linfócito T e induçäo da leucemia linfoma T do adulto pelo HTLV I / Lymphocyte T activation and adult T lymphoma-leukemia induction by HTLV I

A infecçäo pelo vírus linfotrópico de célula T, tipo I (HTLV I), endêmica em algumas regiöes do mundo, ganha conotaçäo principalmente pelo fato de induzir a leucemia linfoma T do adulto e paraparesia espástica tropical/mielopatia associada ao HTLV I. O conhecimento da fisiopatologia da transformaçäo da célula T auxilia tanto a compreensäo das vias normais de ativaçäo/proliferaçäo do linfócito, como no mecanismo de aparecimento de doenças linfoproliferativas. As estratégias usadas pelo vírus para induzir à proliferaçäo celular afeta o ciclo celular em diferentes estágios e em diferentes vias de sinalizaçäo. Seräo analisadas as principais vias envolvidas nessa questäo e alguns mecanismos de açäo do vírus.