The relationship between serum immunoglobulin levels and pulmonary involvement in systemic sclerosis

Objective. To examine the relationship between serum immunoglobulin (Ig) le vels and pulmonary function in patients with systemic sclerosis (SSc). Methods. Twenty-four patients with SSc who had at least 2 sets of pulmonary function tests (PFT) at intervals of more than one year were eligible. Mul tiple linear regression models were constructed for prediction of the annua lized rates of change of forced vital capacity (FVC), carbon monoxide diffu sing capacity (DLco), and DLco per unit alveolar volume (K-co). Results. The rates of change of FVC and K-co correlated with the annualized rate of change of IgG (p < 0.001 and p = 0.005, respectively), and the rat e of change of DLco correlated with the serum IgM level at the first PFT (p = 0.020) and with the annualized rate of change of IgG (p = 0.007). Conclusion. The rates of change of serum Ig levels are associated with thos e of pulmonary function in SSc. Use of this model may assist investigation of pulmonary involvement.