GENERATION OF INTERLEUKIN-2-SECRETING MELANOMA CELL-POPULATIONS FROM RESECTED METASTATIC TUMORS

This study aimed to determine the feasibility of producing patient-spe cific, interleukin-2 (IL-2)-secreting tumor cell vaccines for the trea tment of metastatic melanoma. Primary turner cell cultures were establ ished from 26/33 resected metastatic melanoma samples. Recombinant ret roviral gene transfer and expression in these cultures was optimized u sing an amphotropic, defective retrovirus carrying the LacZ gene. All cell cultures were infectable; those that proliferated more rapidly we re infected at a higher frequency. Addition of fibroblast growth facto r to the culture medium increased the rate of cell proliferation and t he efficiency of infection. A single infection with an identical retro virus carrying a human IL-2 cDNA resulted in the generation of unselec ted cell populations secreting up to 300 units IL-2/10(6) cells.48 hr. Multiple infections increased the level of IL-2 secretion to 5,000 un its/l0(6) cells.48 hr. The recombinant viral genome could be detected at approximately single copy in the multiply infected cells; no helper virus was detected. IL-2 secretion from infected cultures was maintai ned following cryopreservation and x-irradiation. These data demonstra te that heterogeneous tumor cell populations secreting IL-2 can be gen erated from individual patients to be used as autologous, irradiated c ell vaccines.