Effectiveness of neuraminidase in experimental immunotherapy of two murine pulmonary carcinomas

The effects of direct intratumoral inoculation with Vibrio cholerae neuraminidase and inoculation of tumor-bearing mice with tumor cells incubated with neuraminidase in vitro were studied in C57BL/6 X DBA/2 F1 mice bearing s.c.-transplanted, methylcholanthrene-induced pulmonary squamous cell or Lewis lung carcinomas. The growth of the squamous cell tumor was more greatly inhibited by both treatments than was the Lewis lung tumor. In the squamous cell tumor-bearing mice, both modes of neuraminidase treatment depressed tumor growth by approximately 80%. However, 20% of the mice in the group treated with the neuraminidase-incubated squamous cell vaccine and 10% of those treated intratumorally underwent total tumor regression and developed specific immunity to the squamous cell tumor. although the growth rate of the Lewis lung tumor was suppressed by both types of treatment, the direct intratumoral neuraminidase treatment group underwent a greater depression in tumor growth (73 versus 42%). A possible explanation of the different results of the two treatments in squamous cell and Lewis lung tumor systems may be based on tumor etiology and cellular composition.