Repeated measurements of serum immunoglobulin-free light chains in early sarcoidosis.

Serum immunoglobulin free light chains (LC) are frequently increased in chronic active sarcoidosis but rarely in disease of less than 2 years duration. LC were re-measured in 19 sarcoidosis patients who were previously examined during early disease. At first examination LC were elevated in only 4 patients; all of them had achieved normal values at second LC measurement, at an average of 28 months later, in parallel with remission or inactive sarcoidosis in most cases. Elevated LC appeared eventually in 2 patients with clinical evidence of active sarcoidosis, but not in other patients with a similar clinical course. The frequent elevation of LC in chronic active sarcoidosis is, in most cases, dependent on a year-long stimulation of the immune system, longer than has been present in this series.