Browsing by Author "Melo, A."
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- Expansion of circulating Foxp3+D25bright CD4+ T cells during specific venom immunotherapyPublication . Pereira-Santos, M. C.; Baptista, A. P.; Melo, A.; Alves, R. R.; Soares, R. S.; Pedro, E.; Pereira-Barbosa, M.; Victorino, R. M. M.; Sousa, A. E.BACKGROUND: Venom immunotherapy (VIT) induces long-lasting immune tolerance to hymenoptera venom antigens, but the underlying mechanisms are not yet clarified. Regulatory T cells are thought to play an important role in allergic diseases and tolerance induction during specific immunotherapy. AIM: Characterize longitudinally the impact of VIT on the pool of circulating regulatory T cells. METHODS: Fourteen hymenoptera venom-allergic patients with severe reactions (grades III-IV) were studied before, 6 and 12 months after starting ultra-rush VIT. Freshly isolated peripheral blood mononuclear cells were surface stained with a panel of markers of T cell differentiation and intracellularly for CTLA-4 and Foxp3 and analysed by flow cytometry. foxp3 mRNA was quantified by real-time PCR. VIT responses were assessed by measuring specific IgG4 and IgE levels. Eleven individuals with no history of insect venom allergy were studied as controls. RESULTS: VIT induces a significant progressive increase in both the proportion and the absolute numbers of regulatory T cells defined as CD25bright and/or Foxp3+ CD4+ T cells. These changes are not related to alterations in the expression of activation markers or imbalances in the naïve/memory T cell compartments. foxp3 mRNA levels also increased significantly during VIT. Of note, the increase in circulating regulatory T cell counts significantly correlates with the venom-specific IgG4/IgE ratio shift. CONCLUSION: VIT is associated with a progressive expansion of circulating regulatory T cells, supporting a role for these cells in tolerance induction.
- Splenic lymphoma with villous lymphocytes in two sistersPublication . Ribeiro, I.; Costa, M. M.; Fernandes, B. A.; Sousa, I.; Melo, A.; Parreira, A.; Uva, L. S.Splenic lymphoma with villous lymphocytes is a new entity characterised by the presence of atypical lymphocytes in the peripheral blood and bone marrow, and splenic infiltration in the white and red pulp. Cell membrane markers are those of a B mature cell, and no particular chromosomal abnormalities have been associated with this disease. A case of this rare lymphoma occurred in two sisters. Histological examination of splenic tissue was identical in both cases, with the same immunological surface markers, although the clinical and laboratory features were different. Karyotype analysis showed an abnormal pattern in one case; no environmental causative factor could be detected. Familial cases of other lymphoproliferative disorders have been reported, but no consistent common link has been found. It is suggested that further reports of this lymphoma, including cytogenetic and molecular studies, may provide a better understanding of the aetiology.