Hodgkin and Sternberg Reed (H and SR) cells, the putative malignant cells of Hodgkin's disease carry regularly T-cell activation antigens, like CD30 and CD25 (low affinity IL-2 receptor). We have investigated the Hodgkin cell line L540, bearing characteristic markers of H and SR cells for its expression of the low affinity IL-2 receptor (IL-2R) and for IL-2. Expression of the low affinity IL-2R was found on mRNA level, by detection of specific 3.5 kb and 1.4 kb mRNA and on the protein level by immunoprecipitation of a 55,000 mol. wt molecule from detergent extracts of surface iodinated cells, however IL-2 specific mRNA was not detected. Scatchard plot analysis revealed the presence of 2 x 10(3) high affinity IL-2Rs. Crosslinking experiments directly demonstrated the high affinity IL-2R to consist of the 55,000 mol.wt light chain (L), and the 70/75,000 (H1/H2) heavy chains. IL-2 was rapidly internalized by these receptors, suggesting that they can be functional. The expression of functional IL-2Rs might be involved in induction or differentiation of Hodgkin's disease.