Circulating nerve growth factor in primary and secondary Raynaud's syndrome - Results of a pilot study

Background: In this pilot study we examined circulating concentrations of nerve growth factor (NGF) in controls and patients suffering from primary or secondary Raynaud's syndrome and determined their relation to digital vasospasm. Patients and methods: Eighteen controls, 16 patients with primary RP and 19 patients with systemic sclerosis (SScl) were included. Degree of vasospasm was graduated according to the degree of plethysmographically measured vasospastic reaction after cold test. A diary was handed out for documentation of the daily number and duration of RP during a period of 16 days. Circulating NGF levels were analysed by a commercial ELISA (Promega Inc., USA). Results: SScl-patients were significantly older (p < 0.0001) and more severely affected by spontaneously occurring RP (p = 0.03), whereas the severity of the vasospastic reactions after a standard cold test were not significantly different between the groups (p = 0.09).Within each study group and between the study groups elevated NGF levels were observed only in SScl-patients after thermal provocations (p = < 0.05). In a correlation analysis restricted to patients with PRP or SRP, the degree of vasospasm after cold testing as well as the intensity of Raynaud's symptoms were not correlated with NGF-levels (p = n.s.). Conclusions: Our results do not support the hypothesis that NGF plays a major role in the generation of vasospasm in Raynaud's phenomenon.