Tumor necrosis factor-alpha expression in human primary malignant malanoma and it relationship to tumor infiltration by CD3+ cells.

Optimal conditions for immunohistochemical staining of tumor necrosis factor-alpha (TNF-alpha) in paraffin-embedded tissue sections were established to investigate TNF-alpha expression in human primary malignant melanomas. Seventeen malignant melanomas of the nodular (NMM) and superficially spreading (SSM) subtypes were analyzed. Twelve of these were TNF-alpha+, while 5 did not stain for the cytokine. To evaluate how TNF-alpha expression affected the immune response to the tumors, infiltration by CD3+ and mac387+ cells was investigated in NMM. TNF-alpha expression seemed to selectively affect the capability of T cells to infiltrate the tumors since TNF-alpha+ tumors were found to have significantly lower levels of infiltrating CD3+ cells, while there was no difference in numbers of mac387+ cells. These results demonstrate that TNF-alpha is variably expressed in primary malignant melanoma in vivo and that the T-cell response to TNF-alpha-expression NMM is inhibited.