Suppression of natural xenophile antibodies with the novel immunomodulating drug leflunomide.

NATURAL xenophile antibodies (NXA) and induced xenophile antibodies (XA) are considered a major barrier to organ transplantation between phylogeneticaliy discordant species and are held to be responsible for hyperacute and acute rejection of xenogeneic organs.! The aims of this study were (1) to analyze the kinetics of NXA and XA in the xenogeneic model "rat antihuman," which allows experimental manipulation, and (2) to manipulate NXA and XA production by the new immunomodulating drug leftunomide (LF). LF is thought to preferentially inhibit T-dependent B-Iymphocyte proliferation by antagonizing a T-helper cell-derived soluble, B-cell activating factor, possibly an interleukin.