Abstract
Introduction: :
Pars planitis (PP) is a type of intermediate uveitis. The clinical presentation of PP is chronic and insidious. Despite the cause of PP remains unknown, it has been suggested that participation of T cells could play an important role in the development of the disease. In the last years it has been reported that some pathological conditions characterized by the antigen persistence or chronicity are associated with the expansion of unconventional T cells bearing CD57.
Purpose: :
The aim of this work was to evaluate the phenotypic characteristics of CD57+ T cells and its association with effector function.
Methods: :
We determined on peripheral blood mononuclear cells from 10 patients with PP and 10 age–matched healthy controls (HC) the expression of CD4, CD8, and CD57. Results were analyzed by flow–cytometry and U–Mann Whitney rank sum test was used for statistical analysis.
Results: :
CD4+ T cells in PP patients was 47% ± 5 vs 41% ± 5 in HC; CD8+ T cells in PP patients was 35% ± 4 vs 30% ± 4 in HC; CD57+ T cells in PP patients was 31% ± 6 vs 10% ± 3 in HC (p=0.007); CD4+CD57+ T cells in PP patients was 6% ± 1 vs 2 ± 0.1 in HC (p=0.02); CD8+CD57+ T cells in PP was 12% ± 2 vs 5% ± 0.6 (p=0.007). In order to known if the CD8+ CD57+ T cells could play a role as memory/effector cells we determined the surface expression of CCR7, and intracellular expression of perforin and granzime A on CD57+ and CD57– T cells only in patients with PP. Results: Percentage of CCR7+CD57– T cells 37 ± 5 vs percentage of CCR7+ CD57+ ± 1 (p<0.001); Percentage of CD57– perforin+ T cells 17 ± 7 vs percentage of CD57+ perforin+T cells 56 ± 3 (p=0.006); percentage of CD57– granzyme+ T cells 37 ± 10 vs percentage of CD57+granzyme+ 87 ± 7 (p=0.01).
Conclusions: :
The function of CD57+ T cells remains unknown, some authors have suggested that expression of CD57 on T cells is a differentiation event in late immune responses. Our findings showed that CD57+ T cells are increased in PP patients. The subpopulation of CD57+ T cells showed a phenotype associated to effectors functions, perforin+granzyme+CCR7–, suggesting that CD57+ T cells could be effectors cells in process of migration to specific areas of inflammation contributing with the pathogenesis of the immune injury in PP.
Keywords: uvea • immunomodulation/immunoregulation • immune tolerance/privilege