CHARACTERIZATION OF TONSILLAR IL10 SECRETING B CELLS AND THEIR ROLE IN THE PATHOPHYSIOLOGY OF TONSILLAR HYPERTROPHY

LINDYBETH SARMIENTO VARON; JAVIER DE ROSA; ARIEL BILLORDO; BAZ, PLACIDA; PABLO MARIANO FERNÁNDEZ; ANDRÉS BLANCO; ELOÍSA I. ARANA

Congreso; Biociencias 2017; 2017

The immune actions of tonsillar B cells (Bc) must be tightlyregulated to balance the protection against virulent germs and the tolerance toharmless flora and innocuous Ags in food and air. Despite the logic of suchpresumption, the potential role of tonsils in oral tolerance induction has notbeen completely elucidated so far. The aim of our work was to test the abilityof tonsillar Bc to secrete IL10 (regulatory cytokine) and to assess thephysiological relevance of this population. Allmeasurements were done by FACS. We determined the phenotype of tonsillar IL10 secreting Bc(tBregs). Also, we found that the frequency of tBregs as determined by FACS upon 72 hs stimulation ex vivo, via TLR9 and CD40L, depended on the cause of surgery. The hypertrophied(HT) tonsils´ samples showed a significantly (p<0.05) lower percentage of tBregs (4.4±0.4)compared to those from recurrent tonsillitis (RT, 9.9±1.5) as well as a significantly(p<0.05) higher proportion of the germinal center (GC) population (23.8±4.3) than those from children with RT (7.9±1.8). Acomparative increment of the GC percentage was not accompanied by aproportional growth of the memory B cell population in those HT samples. Incontrast, these samples displayed a significantly (p<0.05) lower percentageof the eBm5 subset (7.8±0.5) than RT samples (15.5±2.1), indicative of aputative blockade between the GC and memory B cell stages on HT patients.Collectively, our results demonstrate that adefective tBregs compartment indicates an increase in the proportion of GC in vivo and therefore unrestrained Tfh function, suggesting thatTfh are a target population of tBreg function. Finally,tBreg modulated TNFaintracellular expression by CD4+ cells in co-cultures of autologous tonsillarlymphocytes. Our findings provide greater insight into the role of tBregs in GC reactions andcharacterized for the first time their involvement in the pathogenesis oftonsillar dysfunction