MAGE-3 IMMUNOREACTIVITY IN FORMALIN-FIXED, PARAFFIN-EMBEDDED PRIMARY AND METASTATIC MELANOMA - FREQUENCY AND DISTRIBUTION

Monoclonal antibody 57B specifically detects MAGE-3 gene protein expre ssion, MAGE-derived peptides are recognized by CD8(+) T cells and appl ied in immunotherapy, We examined formalin-fixed, paraffin-embedded ti ssue of 61 melanoma (primary, n = 40; metastatic, n = 21) and 46 contr ol cases (junctional, dermal, compound, Spitz, Reed, and balloon-cell nevi) by immunohistochemistry using the alkaline phosphatase anti-alka line phosphatase method after antigen retrieval, Immunoreactivity was rated positive at 20 positive cells per tumor or more, Staining patter n was homogeneous, scattered, or focal, AU. control samples and intern al controls were immunonegative. Staining with monoclonal antibody 57B showed a specificity of 100% with a sensitivity of 44%, Immunopositiv ity (overall, 44% of melanomas) increased along with tumor, node, and metastasis stage; pT1 showed 15%, pT2 22%, pT3a 29%, pT3b 45%, pT4 100 %, pTxN1 60%, and pTxNxM1a 63% of samples positive, The staining patte rn was homogeneous on pT1 to pT3a tumors, homogeneous or focal in pT3b and pT4a, and homogeneous, focal, or scattered in pTxN1 and pTxNxM1a, The frequency of immunopositivity relates well to data on mRNA expres sion using reverse transcriptase polymerase chain reaction in a subgro up analyzed by both methods, Monoclonal antibody 57B can be used to al low profiling of melanomas using routine archival tissue, when conside ring immunotherapeutic approaches involving MAGE-3-derived epitopes.