The ideal biological response modifier.

: The current focus on interleukin-2 typifies the transition in cancer immunotherapy from nonspecific immunostimulants that are broadly supportive to highly defined cytokines with greater stress on treatment. With the introduction of lymphokine-activated killer cells, there was a parallel shift in emphasis from the use of allogeneic adoptive lymphocytes to in vitro expanded autologous cells. On the assumption that there should be a place for a more complete biological response modifier (BRM) applicable as a fundamental agent that would provide maximum support for all treatment modalities and that might facilitate the adoptive use of incompatible mononuclear cells when needed, an attempt was made to draw on the extensive experience with the large number of BRMs that have been studied to define the characteristics and therapeutic activities of an agent that would be ideally suited. It is ironic that the mitogenic lectins have tended to be overlooked in BRM classifications, but compelling evidence suggests that PHA-L4, the L4 isolectin of phytohemagglutinin, might at least partially fulfill all of the criteria of an ideal BRM.