Effect of local sympathectomy on 24-h changes in mitogenic responses and lymphocyte subset populations in rat submaxillary lymph nodes during the preclinical phase of Freund's adjuvant arthritis

Wistar male rats received a bilateral superior cervical ganglionectomy or s ham-operation and 10 days later were injected with Freund's complete adjuva nt or its vehicle. Two days later, rats were killed at six different time i ntervals throughout a 24-h cycle. The mitogenic effect of lipopolysaccharid e (LPS) and concanavalin A (Con A) and the relative size of lymphocyte subs et populations were measured in submaxillary lymph nodes. Cells from sympat hectomized lymph nodes showed a lower response to Con A. Freund's adjuvant injection decreased amplitude of daily rhythm in Con A response, an effect prevented by denervation. Generally, ganglionectomy increased Con A respons e at the early phase of arthritis. Acrophases for Con A and LPS effect occu rred at early afternoon and did not change after ganglionectomy. Administra tion of Freund's adjuvant caused a IO-h advance in acrophase of LPS mitogen ic activity, an effect prevented by ganglionectomy. Significant 24-h rhythm s were observed in relative size of lymph node B and T cells. Denervation a ugmented amplitude of rhythm in B cells in adjuvant's vehicle-injected rats . As far as T lymphocyte subsets, acrophases occurred at the afternoon (CD4 (+) and CD4(+) -CD8(+) cell types) or at night (CD8(+) cell types). Immuniz ation augmented amplitude of 24-h rhythms in CD4(+)-CD8(+) cells regardless of innervation whereas denervation counteracted the suppression of daily r hythm in CD8(+) cells seen in arthritis. The results indicate that some of the changes seen in 24-h organization of immune responses in lymph nodes at an early phase of arthritis are modified by severing the local sympathetic nerves. (C) 2001 Elsevier Science B.V. All rights reserved.