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

Objective. To examine the relationship between serum immunoglobulin (Ig) levels 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. Multiple linear regression models were constructed for prediction of the annualized rates of change of forced vital capacity (FVC), carbon monoxide diffusing capacity (DL(co)), and DL(co) 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 rate of change of DL(co) correlated with the serum IgM level at the first PFr (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 those of pulmonary function in SSc. Use of this model may assist investigation of pulmonary involvement.