Differential HNK1 Expression on Cultured T Cells From Patients With Allergic Conjunctivitis

Abstract

Introduction: : T cells play an important role in the immune pathogenesis of allergic conjunctivitis (AC). It has been demonstrated that CD4+ T cells infiltrate the conjunctiva and produce large quantities of IL–4 and IFN–g. HNK1 is a sulphated polysaccharide expressed on unconventional T cells and its function is related with late immune responses.

Purpose: : The aim of this work was to evaluate HNK1 expression on T cells and the pattern of cytokine production in cultured cells from patients with AC.

Methods: : Patients were divided into two groups: Group A were patients with the clinical diagnosis of AC and skin prick test positive to Dermatophagoides pteronyssinus (Der p) (n=4). Group B were patients with the clinical diagnosis of AC and skin prick test negative to any allergen (n=4). Peripheral blood mononuclear cells were cultured and stimulated with optimal concentrations of Der p for 7 days, after that cells were labelled with fluorescent antibodies against HNK1, CD4, IFN–g and IL–4. Results were analyzed by flow–cytometry and U–Mann Whitney rank sum test was used for statistical analysis.

Results: : HNK1 co–expression on CD4+ T cells in group A was 11% ± 1.4 vs 24.2% ± 5.4 in group B (p=0.057); Intracellular expression of IFN–g on CD4+HNK1+ T cells in group A was 64% ± 12 vs 63% ± 20 in group B; intracellular expression of IFN–g on CD4+HNK1– T cells in group A was 15% ± 5 vs 24 ± 4 in group B (p=0.057); Intracellular expression of IL–4 on CD4+HNK1+ T cells in group A was 54.2% ± 10 vs 72% ± 10 in group B; Intracellular expression of IL–4 on CD4+HNK1– T cells in group A was 13% ± 2 vs 24% ± 6 in group B (p=0.029).

Conclusions: : The function of CD4+HNK1+ T cells is related with modulation of late immune responses trough cytokine production. Here we found that patients clinically diagnosed with AC and without reaction to any allergen in the skin prick test showed an increased expression of HNK1 on CD4+ T cells after 7 days of culture; when the intracellular cytokine production was evaluated we found that, in both groups, the main production of cytokines reside on CD4+HNK1+ T cells subset, however only in the group of patients with clinical diagnosis of AC and skin prick test negative we found an increased number of CD4+HNK1– IFN–g+ and CD4+HNK1–IL–4+ T cells. Our results suggest different immune mechanisms in the pathogenesis of allergic conjunctivitis.

Keywords: conjunctivitis • immunomodulation/immunoregulation • cornea: basic science