RECOGNITION BY HUMAN V-GAMMA-9 V-DELTA-2 T-CELLS OF MELANOMA-CELLS UPON FUSION WITH DAUDI CELLS/

Daudi Burkitt's lymphoma cells, unlike other tumor cell lines, stimula te human T cells coexpressing the variable (V) region genes TCRG-V9 an d V TCRD-V2 to proliferate and secrete lymphokines. Hybrids, derived b y the fusion of Daudi cells with the human melanoma cell line MZ2-MEL 2.2, retain the morphology of melanoma cells. Unlike the parental mela noma cell line, these Daudi x MZ2-MEL 2.2 hybrids stimulate secretion of tumor necrosis factor (TNF) and granulocyte/macrophage colony stimu lating factor (GM-CSF) by CD4-positive V gamma 9/V delta 2 T-cell clon es. Whereas the stimulator phenotype of Daudi cells behaves as a domin ant trait in Daudi x melanoma hybrids, the expression of B-cell differ entiation markers is suppressed. Thus, the gamma/delta T-cell ligand e xpressed by Daudi cells behaves as a dominant tumor antigen in Daudi x melanoma hybrids and is unrelated to the differentiated B-cell phenot ype. Dominant expression of the Daudi ligand for human V gamma 9/V del ta 2 T cells in these hybrids may provide a basis for defining the sti mulatory principle at the molecular level.