Tumor immunogenicity--the prime determinant of the nutritional influence on the host-tumor relationship.

The influence which malnutrition plays on the host-tumor relationship is controversial because of the disparity of human and rodent tumors, a critical difference being the minimal immunogenicity of human tumors and the variable antigenicity of rodent tumors. The hypothesis we tested is that the influence of malnutrition on tumor growth is a result of the immunogenicity of the host's tumor. C-1300 neuroblastoma (NB) is an immunogenic tumor by in vivo and in vitro assessment while the histologically identical TBJ-NB clone is non-immunizing. Isogeneic A/J mice were malnourished with 2.5% protein chow and were inoculated with C-1300-NB or TBJ-NB; either serial tumor volumes were assessed by three-dimensional measurement or animals were serially killed and tumor weight/carcass weight ratios (TW/CW) were calculated. Non-immunogenic TBJ-NB grew more rapidly than C-1300-NB in both control and malnourished groups, but there was no difference in either tumor size or TW/CW ratios between the two TBJ-NB nutritional groups. Contrasting with these data were immunogenic C-1300-NB in that the tumor grew significantly better in malnourished mice (tumor volume p less than 0.05 day 12 and 14; TW/CW p less than 0.026 by day 21). Prior whole-body irradiation abrogated this difference. These data demonstrate that for tumors differing only in antigenicity the influence of malnutrition is on that tumor which induces an immunologic antitumor response.