These data are compared with our own recent studies showing that IL-4 impairs CD8+ T-cell-mediated immunity against the mastocytoma cell line P815 expressing the immunogenic HLA-CW3 gene; moreover, we hypothesise that quantitative and qualitative differences in the HLA-CW3-induced CD8+ T-cell response impair control of tumour growth and aid the development of secondary tumours.
After oral immunization of BALB/c mice with two 1 x 10(9) colony forming unit doses given 21 days apart, CVD 908 omega (delta aroC::Ptac-gp63) elicited a broad T cell-mediated immune response against L. m. mexicana gp63 as demonstrated by: (1) lymphoproliferative response to fixed whole L. m. mexicana promastigotes; (2) activation of IL-2 (but not IL-4)-producing lymphocytes; (3) appearance of cytotoxic T cells against mouse mastocytoma cells expressing gp63.