CONICET | Buscador de Institutos y Recursos Humanos

Tonsils are secondary lymphoid organs which aremostly B-cell (Bc) maturation and differentiation sites. They show similarities with lymph nodes and couldparticipate as effector organs of local systemic type as well as inductivesites of mucosal immunity. Their immune actions must be tightly regulated to balancethe protection against virulent germs and the tolerance to harmless flora andinnocuous Ags in food and air. Despite the logic of such presumption, and therelevance of the issue in light of the importance gained by the mucosal routeof vaccine administration, the potential role of tonsils in oral toleranceinduction has not been completely elucidated so far. As it is conceivable thatalteration of the immune equilibrium activation/regulation may trigger recurrenttonsillitis and hypertrophy leading in turn to tonsillectomy, the aim of ourwork was to test the ability of tonsillar Bc to secrete IL10 (regulatorycytokine) and IL17 (pro-inflammatory cytokine). The frequency of tonsillar IL10secreting Bc (8,9%±3% of total Bc, B10) and IL17 secretingBc (11,9%±5% of total Bc, B17) was determined by FACSupon 72 hs stimulation ex vivo, via TLR9 andCD40L. Also, we demonstrated that IL10 secreting B cells were enrichedwithin both the IgM memory (CD19+CD24highCD27+CD38+low)and the transitional T3 (CD19+CD24intCD27-CD38+)B-cell subsets, in agreement with previous reports on Bc isolated fromPBMC. Interestingly, we found co-expression of IL10 and IL17 following theindicated stimulation and alternative ones (i.e IL2+IL4, differenttime points). On the other hand, we did not detect any co-expression patternwith other pro-inflammatory cytokines (IL6). Finally, we established a negativecorrelation between the percentage of B10 and B17 populations and the fraction ofproliferating CD3+ (autologous) in co-culture. Importantly, wepostulate that these findings might apply to other mucosal human Bc, as in gut.