Background T regulatory cells (Tregs) are inversely correlated to disease activity in systemic lupus erythematosus (SLE). However, little is known concerning the influence of immunosuppressive agents on Tregs and their kinetics, which was the objective of this study.
Methods Thirty five lupus patients (29 females, 6 males, mean age 42.4±12.8 years, mean disease duration 97.5±16.2 months), in whom a dose increase of current drugs or administration of a new drug was required, were included. Tregs (CD4+CD25highFOXP3+) were prospectively assessed by flow cytometry every month for intravenous (iv) and quarterly for oral regimens. Clinical assessment was made with SLE Disease Activity Index (SLEDAI). Statistical analysis was performed with Student's t-test or Mann-Whitney U test; p<0.05 was considered significant.
Results In total, 44 cases of SLE relapse were treated with iv cyclophosphamide (n=10), iv methylprednisolone (n=7), iv immunoglobulins (IVIGs, n=5), oral methylprednisolone (n=8), oral methylprednisolone and azathioprine (n=8) and hydroxychloroquine (n=6). Cyclophosphamide, iv methylprednisolone and IVIGs resulted in a significant increase of Tregs (4.2±1.6 to 10.1±5.7 cells/mm3, 2.9±1.3 to 10.6±4.8 cells/mm3 and 5.6±2.7 to 15.2±6.3 cells/mm3 respectively, p<0.05). Oral methylprednisolone, alone or combined to azathioprine, led to significant Tregs increment (7.4±2.5 to 11.8±3.8 cells/mm3 and 5.1±2.4 to 9.4±3.6 cells/mm3 respectively, p<0.05). Likewise, hydroxychloroquine resulted in significant Tregs increase (8.2±2.4 to 12.8±2.7 cells/mm3, p<0.05). Time to Tregs recovery was significantly shorter with iv methylprednisolone and IVIGs, compared to cyclophosphamide (1.4±0.5, 1.6±0.9 and 4±1.5 months respectively, p<0.05).
Conclusions Tregs increment during SLE remission is independent of the therapeutic regimen used and probably represents an epiphenomenon. Time to Tregs restoration was significantly shorter in patients treated with iv methylprednisolone and IVIGs, compared to cyclophosphamide pulse therapy.
Disclosure of Interest None declared
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