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Lymphocyte traffic changes induced by monolateral vagal denervation in mouse thymus and peripheral lymphoid organs
A Antonica1, E Ayroldi, F Magni
1Istituto di Patologia Generale, Cattedra de Fisiologia Umana, Universitá de Perugia, Italy.
Insights
Vagotomy (vagal nerve denervation) temporarily increases immature lymphocyte release from the thymus to the spleen and lymph nodes. This suggests the vagal nerve influences lymphocyte traffic within the thymus.
Area of Science:
- Immunology
- Neuroscience
- Vascular Biology
Background:
- The thymus is crucial for T-cell maturation and export.
- The vagus nerve plays a role in regulating various physiological processes.
Purpose of the Study:
- To investigate the effect of vagotomy on lymphocyte release from the mouse thymus.
- To explore the role of the vagus nerve in immune cell trafficking.
Main Methods:
- Cervical vagotomy was performed on mice.
- Thymocytes were labeled in situ with fluorescein isothiocyanate (FITC).
- Flow cytometry was used to analyze lymphocyte populations (CD4, CD8) in thymus, spleen, and lymph nodes.
Main Results:
- Vagotomy transiently increased the export of immature CD4+CD8+ (DP) and CD4-CD8- (DN) thymocytes.
- The percentage of mature CD4+CD8- and CD4-CD8+ (SP) thymocytes decreased in peripheral lymphoid organs.
- Increased lymphocyte release was observed 24 and 48 hours post-vagotomy.
Conclusions:
- The vagus nerve may facilitate the egress of mature lymphocytes from the thymus.
- Vagotomy-induced changes in lymphocyte populations are likely not due to stress.
- The vagal nerve's influence on lymphocyte traffic occurs at the thymic cortico-medullary junction.
Abstract:
In this report we show that after monolateral vagal denervation (vagotomy), performed at the cervical level, a transient effect, lasting about 24h, 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 CD8alpha 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.