FOXP3+ and CD39+ regulatory T cells in subtypes of cutaneous lupus erythematosus

Lupus erythematosus (LE) is an autoimmune disease in which regulatory T cells play a pathogenetic role.

We aimed to assess and compare the quantities of lesional Tregs in subtypes of cutaneous LE (CLE) including chronic discoid LE (CDLE), LE tumidus (LET) and subacute CLE (SCLE).

Thirty-nine patients with CLE were enrolled in the study. Immunohistochemistry was performed for CD4, CD8, FOXP3 and CD39.

We studied nine CDLE patients, 21 LET patients and nine patients with SCLE. SCLE lesions [37 (0-134)] showed a significantly (P = 0.024) decreased percentage of CD4+ cells when compared with CDLE [125 (0-146)] and LET [124 (0-240)] lesions. Moreover, the CD4/CD8 ratio in SCLE lesions [0.7 (0.5-1.8)] was significantly (P = 0.027) decreased when compared with CDLE [1.9 (1.5-2.8)] and LET [1.6 (0.8-2.9)] lesions. FOXP3 immunopositivity was significantly (P = 0.017) decreased in LET [0 (0-6)] and SCLE [1 (0-2)] lesions when compared with CDLE [6 (0-38)]. Moreover, in LET [2 (0-6)] and SCLE [2 (0-2)], we observed a significantly (P = 0.0049) diminished CD39-immunoreactivity when compared with CDLE [4 (2-12)]. CD4+ cell count is a significant (P = 0.0133) negative predictor for the diagnosis of SCLE (Odds ratio 0.978, 95% CI 0.960-0.99).

Our data indicate that there are differences in quantities of lesional T helper cells, CD4/CD8 ratio and Tregs among subtypes of CLE. Interestingly, a more significant decrease in Tregs, which likely reflects greater loss of immune-tolerance, is observed in the more photosensitive subtypes of CLE such as SCLE and LET.