CHANGES IN CELLS SUBSETS PRESENT IN THE THYMUS AFTER SYSTEMIC TH1 INFLAMMATORY/INFECTIOUS PROCESSES

NATALIA S. BAEZ ; FABIO M. CERBAN ; MARIA CECILIA RODRIGUEZ GALAN

Congreso; REUNIÓN DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA; 2013

We have demonstrated that during systemic inflammatory/infectious processes, peripheral mature T cells are able to enter the thymus. These cells could be distinguished from resident thymocytes based on the expression of high levels of the surface marker CD44. In this work we further characterized peripheral T cells residing in the thymus but also evaluated maturation changes that experience resident thymocytes during inflammatory/infectious Th1 processes. We found that resident SP (simple positive) thymocytes (CD44lo) are able to sense systemic inflammatory stimuli by changing its phenotype similar to mature T cells in secondary lymphoid organs (SLO). T cells found in SLO express high levels of Qa2 and low levels of CD24. In contrast, immature SP thymocytes expressed the opposite phenotype (Qa2lo-CD24hi). The inversion in the expression of these markers is expected to happen when recent thymic emigrants contact SLO, however, we observe that under certain Th1 systemic situations (LPS or IL-12+IL-18 in vivo or C. albicans and T. cruzi infections) SP thymocytes adopt the mature phenotype similar to a peripheral T cell (Qa2hi-CD24lo) (p