Cystatin C as a potential marker for relapse in patients with non-Hodgkin B-cell lymphoma.

The concentration of cysteine protease inhibitor cystatin C was determined in sera from 59 patients with non-Hodgkin B-cell lymphoma using ELISA. The sera from 43 age and sex matched healthy blood donors served as controls. Cystatin C was significantly increased in sera of patients without therapy (mean 1136+/-SE 105.7ng/ml, p=0.00001) and with therapy (mean 1073+/-52ng/ml, p=0.001) compared to controls (mean 819+/-28ng/ml). The highest levels were determined in sera of patients with a relapse (mean 1680+/-196ng/ml). By using immunofluorescence staining and confocal microscopy we determined immature dendritic cells as a major population of cystatin C positive cells in affected lymph nodes. Our study reports for the first time that cystatin C is a potential marker for relapse in patients with non-Hodgkin B-cell lymphoma.