INTERLEUKIN-1 PRODUCTION IN TUMOR-CELLS OF HUMAN-MELANOMA SURGICAL SPECIMENS

To determine whether IL-1 alpha and/or IL-1 beta protein is expressed by human melanoma tumor in vivo, we first analyzed nine human melanoma cell lines and optimized the in situ detection of these proteins, Thr ee of the melanoma cell lines stained positively for both IL-1 alpha a nd IL-1 beta using immunohistochemistry (IHC), The specificity of MC w as confirmed by the ability of purified recombinant IL-1 alpha and IL- 1 beta protein to abolish the staining after being adsorbed by their r espective antibodies before use in IHC, The three positively staining cell lines were also the only lines to demonstrate IL-1 production by western blot analysis as well as IL-1 secretion by ELISA, Next we exam ined 29 surgically obtained melanoma tumor specimens (6 primary and 23 metastases) that had been formalin fixed and paraffin embedded. Using the same anti-IL-1 antibodies, 5 of 23 metastatic tumors stained posi tively, None of the 6 primary lesions stained for either IL-1 alpha or IL-1 beta. Comparison of staining pattern performed on serially secti oned tissue using preimmune serum and antibodies against S-100 protein , melanoma-associated antigen (HMB-45), and CD68 (kappa P1), which rec ognizes monocyte-macrophage cell lineage, demonstrates for the first t ime that IL-1 protein is produced by human melanoma tumor cells in viv o. These findings provide the basis for examination of what may be a p reviously unrecognized biologically distinct subset of patients.