Rituximab treatment in pemphigus vulgaris: effect on circulating Tregs

Rituximab (RTX) has been used successfully to treat refractory pemphigus. We aimed to assess the response of pemphigus vulgaris (PV) cases to RTX therapy and its effect on CD4⁺CD25⁺ (T regulatory) cells level. Sixteen PV patients were included in this study, each received one cycle of two RTX infusions (1000 mg on days 1 and 15). Five PV patients served as controls. All cases were on prednisolone ± adjuvant therapy. Pemphigus disease area index (PDAI), autoimmune bullous skin intensity score (ABSIS), anti-desmoglein antibodies, CD4, CD8, CD20 and CD4⁺CD25⁺ levels were assessed at baseline, 3, 6 and 12 months after therapy. Fourteen patients were followed up for a mean duration of 17 while two were lost to follow up 6 months after RTX therapy. A significant decrease in PDAI, ABSIS, Dsg3 (p < 0.0001) was found. The depletion of B cells lasted for 12 months in 11 (69%) patients and for 24 months in 3 (21.4%) patients. There was significant decrease in CD20⁺ and CD4⁺CD25⁺ cells after 12 months of RTX, p values were 0.005 and 0.02, respectively. While no similar change in CD8 and CD4 was found (p = 0.2 for both), no significant change of CD20 and CD4⁺CD25⁺ cells were detected in the control group. In conclusion RTX is safe and effective as an adjuvant therapy in refractory cases of PV. In addition to B cell depletion a significant reduction of T regulatory cells occurs in treated cases which may be due to increased skin homing of these cells.