CONICET | Buscador de Institutos y Recursos Humanos

NOD mice are highly susceptible to develop spontaneous or induced autoimmune diseases like diabetes, thyroiditis, prostatitis and sialadenitis, while C57BL/6 and BALB/c mice are more resistant respectively. It has been suggested that this increased susceptibility could be related to defects in regulatory T cell (Treg) populations. Herein, we analyzed frequencies and absolute numbers of Treg and effector T cells (Teff, T cells with an activated phenotype) in lymph node and spleen cells from NOD, C57BL/6 and BALB/c mice in steady state conditions, when animals show no signs of autoimmunity/inflammatory conditions (aged up to 8 weeks old). No significant differences in the frequencies or absolute numbers of CD4+CD25+Foxp3+, CD4+Foxp3+Helios+ and CD4+Foxp3+GITR+ cell populations from spleen or lymph node cells were observed among mouse strains. Analyses of the mean fluorescence intensity (MFI) values of Foxp3, GITR and Helios also showed no differences among mouse strains; however, the MFI value of CD25 showed a significant decrease in the Treg population from NOD mice when compared to the other strains (p <0.05). When we analyzed the Teff frequencies and absolute numbers in spleen and lymph node cells from mouse strains under study, higher frequencies and absolute numbers of activated (CD4+CD44hiCD62L-) T cells were detected in NOD mice when compared to the other strains. Indeed, the Treg/Teff ratio was significantly decreased in the NOD strain (p <0.05). Our results show that in a steady state, NOD mice that received no treatment and have grown in the same environment/conditions as mice from other strains have similar numbers of Treg and increased amounts of Teff. These results suggest that the Treg/Teff ratio is a good correlation marker for assessing autoimmune susceptibility. These results encourage us to continue analyzing whether this increased susceptibility observed is associated with imbalances or functionality defects in particular Treg subpopulations