Due to their central role in controlling immunity, dendritic cells are logical 
targets for priming naive cytotoxic T lymphocytes against tumour cells. In a 
strictly autologous system, we fused dendritic cells with melanoma cells, both 
of which were derived from patients with metastatic malignant melanoma. 
Hybridomas were positive for major histocompatibility complex (MHC) class II, 
CD40, CD54, CD83, CD86, and the pro-inflammatory cytokine interleukin-12. 
Autologous T lymphocytes were co-incubated with hybridomas. After 6 days, 
in-vitro-primed T lymphocytes revealed a strong proliferation activity and 
released Th-1-associated, but not Th-2-associated, cytokines. Furthermore they 
showed effective anti-melanoma activity, resulting in death of 70 +/- 9% of 
autologous melanoma cells. After depletion of CD4+ cells from the mixed 
population of primed T lymphocytes, the remaining CD8+ cells were able to kill 
63+/-8% of autologous melanoma cells. Following depletion of CD8+ cells, 
however, the cytotoxic capacity of the remaining T lymphocytes caused death in 
only 32+/-6% of autologous melanoma cells. Blocking of MHC class I, but not 
class II, molecules on hybridomas impaired T cell proliferation, secretion of 
Th-1-associated cytokines, as well as the cytotoxic activity of primed T cells. 
These findings strongly suggest that hybridomas deliver melanoma-associated 
antigens via MHC class I molecules to T lymphocytes, resulting in the generation 
of CD8+ cytotoxic T lymphocytes with effective anti-melanoma activity in vitro. 
The data may serve as a basis for the use of hybridomas in the immunotherapy of 
malignant melanoma in vivo.