Proliferative response of fibroblasts to CM from HD and HCL patients. Human dermal fibroblasts (D15-7) were cultured in the presence of 25% CM derived from PBMC of an HD and from an HCL patient (open bars). In a separate experiment, CM was preincubated (1 hour, 37°C) with a neutralizing anti-bFGF antibody (10 ng/mL) before addition to fibroblasts (solid bars). After 48 and 96 hours, proliferation was assessed by ³H-TdR incorporation. Proliferation of cells without CM was considered as 100%.