The TNF family member, a proliferation-inducing ligand (APRIL), has been suggested to act as a costimulatory molecule in T cell responses. However, studies addressing this role in vivo are largely lacking. Here, we evaluated the effects of APRIL on physiological T cell responses in vivo. Although receptors for APRIL are expressed on a subset of T cells, neither TCR transgenic (Tg) T cell responses nor endogenous TCR responses were affected by Tg APRIL expression in vivo. Moreover, APRIL did not significantly enhance the induction of T cell lymphomas upon Moloney murine leukemia virus (MLV) infection. This clearly contrasts current belief and indicates that APRIL does not serve a major role in T cell immunity or lymphomagenesis. However, we did observe a strong increase in erythroleukemia formation after MLV inoculation of APRIL Tg mice. Strikingly, this erythroleukemia-facilitating property of APRIL was confirmed using the erythroleukemogenic Friend-MLV. Erythroleukemia in APRIL Tg mice was characterized by low hematocrits and grossly enlarged spleens with an increased percentage of erythroid precursors. Altogether, these results unveil new proerythroleukemogenic properties of APRIL.
APRIL facilitates viral-induced erythroleukemia but is dispensable for T cell immunity and lymphomagenesis
Hardenberg, G.; Fernandez, L.; Hendriks, J.; Chebli, K.; Jacquet, C.; Sitbon, M.; Hahne, M.; Medema, J. P.
J Leukoc Biol
2008-08-01 / vol 84 / pages 380-388
expression; b-cell; baff; blys; chronic lymphocytic-leukemia; deficient mice; friend-murine leukemia virus; moloney-murine leukemia virus; myeloma cells; necrosis-factor family; receptor superfamily; survival; t lymphocyte; taci