Lectins are widely used in many types of assay but some lectins such as banana lectin (BanLec) are recognised as potent immunostimulators. Although BanLec's structure and binding characteristics are now familiar, its immunostimulatory potential has not yet been fully explored. The synthesis by recombinant technology of a BanLec isoform (rBanLec) whose binding properties are similar to its natural counterpart has made it possible to overcome the twin problems of natural BanLec's microheterogeneity and low availability. This study's aim is to explore the immunostimulatory potential of rBanLec in the murine model. Analyses of the responses of Balb/c- and C57 BL/6-originated splenocytes to in vitro rBanLec stimulation were performed to examine the dependency of rBanLec's immunostimulatory potential upon the splenocytes' genetic background. It is shown that the responses of Balb/c- and C57 BL/6-originated splenocytes to rBanLec stimulation differ both qualitatively and in intensity. The hallmarks of the induced responses are T lymphocyte proliferation and intensive interferon-gamma secretion. Both phenomena are more marked in Balb/c-originated cultures; Balb/c-originated lymphocytes produce interleukin (IL)-4 and IL-10 following rBanLec stimulation. Our results demonstrate that any responses to rBanLec stimulation are highly dependent upon genetic background; they suggest that genetic background must be an important consideration in any further investigations using animal models or when exploring rBanLec's potential human applications.