Increased IL-21 Expression Induces Granzyme B in Peripheral CD5+ B Cells as a Potential Counter-Regulatory Effect in Primary Sjögren’s Syndrome

Abstract EN

Recently, we reported elevated proportions of circulating follicular T helper cells and higher levels of interleukin- (IL-) 21 in primary Sjögren’s syndrome (pSS).

Interaction of invariant natural killer T (iNKT) cells with B cells and granzyme B (GrB) production may be also important in pSS.

Thirty-two pSS patients and 24 healthy controls were enrolled in our study.

We investigated the expression of intracellular GrB and IL-21 receptor (IL-21R) of CD19+CD5+ and CD19+CD5− B cells; furthermore, we determined the IL-21 expression of iNKT cells as well.

We also assessed the proportion of transitional ( C D 19 + C D 24 h i g h C D 38 h i g h ), mature ( C D 19 + C D 24 i n t C D 38 i n t ) and primarily memory ( C D 19 + C D 24 h i g h C D 38 - ) B cells.

CD5+ but not CD5− B cells showed elevated GrB and IL-21R expression in pSS; additionally IL-21 expression of iNKT cells was also elevated.

The ratios of transitional and mature B cells were elevated in pSS, while primarily memory B cell percentages were decreased, which correlated with GrB and IL-21R expression of CD19+ B cells.

Our results suggest that enhanced IL-21R expression of CD19+CD5+ B cells and production of IL-21 by iNKT cells may play an important role in the pathogenesis of pSS by regulating CD19+CD5+ B cell functions and increasing GrB production, presumably leading to a counter-regulatory effect in the disease.