Systemic sclerosis (SSc) and vibration induced white finger syndrome (VWF) are common causes of secondary Raynaud's phenomenon. Previous studies have suggested an increase in inflammation in patients with SSc. Vibration induced white finger syndrome occurs in workers exposed to vibration and is now a prescribed disease. In VWF, although it is recognised that vibration can cause direct damage to blood vessels, it does not explain why only some workers are affected. It is possible that an inflammatory process develops in these patients in the same way as is seen in SSc. Leukotriene B4, produced mainly by polymorphonuclear cells, is a potent mediator of inflammation. The plasma thiol concentration shows the degree of oxidation of plasma and a decreased concentration indicates the increased production of free radicals which are capable of oxidative damage.
In this work, the white blood cell (WBC) production of leukotriene B4 and plasma thiol concentrations were measured in patients with SSc and VWF. Fifty nine patients were studied: 34 had SSc and 25 had VWF. The results were compared with 25 matched normal controls and are expressed as the median and range. After stimulation of the polymorphonuclear cells with calcium ionophore A23187 (1µg/ml), patients with SSc and VWF were found to have significantly increased leukotriene B4 production (23.5 (14.4-44.0) and 26 (14.4-39.4) ng/106 cells, respectively) compared with normal controls (17.2 (6.0-38.0) ng/106 cells). The plasma thiol concentration was shown to be significantly lower in patients with SSc and VWF (445 (375-475) and 450 (417-510) µmol/l, respectively) compared with normal controls (480 (418-555) µmol/l).
Our results show increased leukotriene B4 production and increased free radical activity in patients with SSc and VWF. Although previous indirect evidence has suggested increased WBC activity in patients with SSc, this is reported directly here for the first time. In addition, the possibility of an inflammatory process occurring in patients with VWF, as shown here, has not previously been studied. This may be a further mechanism to explain the poor circulation in the fingers of these patients.