RESUMO
BACKGROUND: Chronic neuropathic pain is often associated with altered immune function and the modulated immune cell response play a role in neuropathic pain by experimental nerve injury. In order to assess the possible changes in lymphocytes function following peripheral mononeuropathy, this study examined the lymphocyte subpopulation of the spleen using the monoclonal antibodies against the membrane surface markers in neuropathic BALB/c mice by a partial transection of sciatic nerve (PST). METHODS: After confirming tactile allodynia by paw withdrawal threshold, the splenic lymphocytes were stained with fluorescein isothiocyanate (FITC)-conjugated anti-mouse CD45R/B220 (B cell) and CD4 (helper/inducer T cell) or with phycoerythrin (PE)-conjugated anti-mouse CD90.2 (total T cell) and CD8 (suppressor/cytotoxic T cell). The proportions of subsets were analyzed using a FACScan laser flow cytometry system on postoperative day 5 and day 18 respectively. RESULTS: PST induced a mechanical allodynia as verified by the von Frey test at both 5 and 8 days postoperatively compared to pre-surgery (P < 0.05). Lymphocyte subpopulation was affected by PST. The proportion of CD4+ subset was significantly larger in the PST group than in the sham operated group on day 5, while the proportion of CD8+ subset was larger on day 18. In the PST group, there were significantchanges in the proportion of CD4+ on day 5 and in the proportion of CD8+ on day 18 (P < 0.05) compared to pre-surgery. There were no significant fluctuations in the proportion of total splenic T cell and B cell subsets of PST group compared to sham operated group. CONCLUSIONS: These results suggest that development of mononeuropathy is responsible for the proportional changes in splenic lymphocyte subsets in mice.