Aim: To evaluate the frequency, phenotype and the potential function of CD57+ T cell subsets in patients with pars planitis.
Methods: CD4+CD57+ and CD8+CD57+ T cells were quantitated in peripheral blood from 15 patients with pars planitis and 15 healthy controls. To evaluate the phenotype and potential function of CD57+ T cell subsets CCR7, CD27, CD28, CD45RA, CD45RO, intracellular IFN-gamma, IL-4, perforin and granzyme-A expression were assessed by flow cytometry.
Results: CD57+ T cells subsets were increased in patients with pars planitis (p = 0.002). The majority of CD4+CD57+ T cells were CCR7-CD27-CD28-CD45RO+, while the most CD8+CD57+ T cells were CCR7-CD27-CD28-CD45RA+. The number of cells positive for intracellular IFN-gamma and IL-4 was higher in the CD57+ T cell populations. A greater number of CD8+CD57+ T cells than CD8+CD57- T cells were positive to perforin (p = 0.006) and granzyme-A (p = 0.01).
Conclusions: CD57+ T cells had a phenotype associated with peripheral memory (CCR7-CD27-CD28-). Cytokine production by CD57+ T cells suggests that these cells may play a role in helper cell regulation. High expression of intracellular proteins involved in cytotoxicity suggests that CD8+CD57+ T cells may play an effector role. Taken together, this study proposes that CD57+ T cells function as memory-effector T cell subsets during pars planitis pathogenesis.