Interleukin-2 receptors in pulmonary adenocarcinoma tissue

We previously reported that the serum soluble interleukin-2 receptor (sIL-2R) level increased with the advance of disease stage in non-small cell lung cancer. The present study was thus conducted to investigate the origin of serum sIL-2R in patients with pulmonary adenocarcinoma. Fresh tumor cell suspensions were prepared from surgically resected specimens of pulmonary adenocarcinoma. They were adjusted to a cell density of 5 x 10(5)/ml and then cultured for 24 h at 37 degrees C. The culture supernatants were collected and assayed to determine the sIL-2R levels using an enzyme immunoassay. The resultant cells were thereafter cytocentrifuged onto glass slides and immunochemically stained with anti-human IL-2R alpha (CD25) monoclonal antibody. In three of six cases examined, a substantial level of sIL-2R was identified in the culture supernatants. In four cases, including those three cases with the presence of sIL-2R in the culture supernatants, various proportions of tumor cells were positively stained with the anti-IL-2R alpha antibody. Further examinations revealed that tumor cells expressed IL-2R alpha (CD25) in seven of 16 cases with pulmonary adenocarcinoma. These results thus suggested that the tumor cells did express IL-2R alpha and release sIL-2R in some cases with pulmonary adenocarcinoma.