Lymphocyte traffic changes induced by monolateral vagal denervation in mouse thymus and peripheral lymphoid organs

In this report we show that after monolateral vagal denervation (vagotomy), performed at the cervical level, a transient effect, lasting about 24 h, was produced on lymphocyte release from mouse thymus to peripheral lymphoid organs (spleen and lymph nodes). Labelling thymocytes in situ with fluorescein isothiocyanate (FITC) we note that the export of immature cells, CD4+CD8+, double positive (DP), and double negative, CD4-CD8- (DN), from the thymus was consistently increased 24 and 48 h after vagotomy. Double staining with anti-L3T4 (CD4) and anti-mouse CD8α showed that the number of DP and DN cells was significantly higher in both spleen and lymph nodes of vagotomized mice compared to controls (sham-operated), whereas the percentage of CD4+CD8- and CD8+CD4-, single positives (SP), was decreased. Considering thymic cellularity and apoptotic values, we exclude the non-specific effect of stress and suggest that this phenomenon could be in part due to a transient lack of the facilitating influence exerted by vagal efferent fibers on lymphocyte traffic at the cortico-medullary junction of the thymic gland, where mature cells, SP, leave the thymus to enter systemic circulation.