dsDNA-, nucleohistone- and DNASE I-reactive T lymphocytes in patients affected by systemic lupus erythematosus: Correlation with clinical disease activity

Objective. To demonstrate the involvement of T lymphocytes reactive to autoantigens in the pathogenesis of autoimmune diseases and to analyse their clinical relevance. Methods. The frequency of T cell clones reactive to double strand DNA (dsDNA), Nucleohistone (NH) complex and Dnase I was calculated for the peripheral blood mononuclear cells (PBMC) of 15 SLE patients and 9 healthy subjects by proliferation assay. Results. DsDNA- and NH-specific T cell clones were found in the majority of the patients analysed (frequency ranging from 2 to 50 clones/10⁷ PBMC), while their absence or very low frequency (2 clones/10⁷ PBMC) was observed in the control PBMC. Their frequency significantly correlated with decreased serum concentrations of C3 and C4 and with the systemic lupus erythematosus disease activity index (P = 0.03). A very low frequency of Dnase I-reactive T cell clones was observed in both SLE and healthy subjects. Conclusion. Our results suggest that dsDNA- and NH-reactive T lymphocytes may be involved in the pathogenesis of SLE and that their quantification in the peripheral blood of patients could be a useful tool to follow the clinical course of the disease.