Inflammation in sympathetic ganglia proximal to sciatic nerve transection in rats

Comparison was made between recruitment of T-lymphocytes and macrophages into lumbar sympathetic ganglia (SGs) and dorsal root ganglia (DRGs) following sciatic nerve transection in rats. In both control and lesioned SGs, resident (ED2+) macrophages expressed less major histocompatibility complex class II (MHC II), but MHC II+ macrophage density was higher, than in equivalent DRGs. The influx of T-cells was larger and the influx and activation of macrophages were more sustained in SGs than in DRGs. Only two of the five subtypes of macrophage that invade lesioned DRGs were recruited to SGs. While some MHC II+ cells phagocytosed dead sympathetic neurones, most phagocytes in SGs lacked a macrophage marker. The different patterns of response between ganglia may provide clues about macrophage involvement in neuronal death and hyperexcitability after peripheral nerve lesions.