In vivo administration of a PKA type I inhibitor (Rp-8-Br-cAMPS) restores T-cell responses in retrovirus-infected mice

Murine AIDS (MAIDS) is caused by infection with the murine leukemia retrovirus RadLV-Rs and is characterized by T-cell anergy and severe immunodeficiency with increased susceptibilty to several experimental opportunistic infections as observed in HIV infection. T cell anergy is associated with an increase of intracellular cAMP level, triggering a multistep pathway involving activation of PKA type I and resulting in inhibition of proximal TCR signaling. We have reviously demonstrated that blocking PKA type I using the selective inhibitor Rp-8-Br-cAMPS, restores T-cell function in vitro in MAIDS as well as in HIV infection. In the present report, we investigated the effect of parenteral administration of Rp-8-Br-cAMPS in mice with MAIDS. We show that the compound is not toxic and partially restores the ex vivo proliferative responses to anti-CD3 mAb, but that it has no effect on the lymphadenopathy and splenomegaly characterizing
the MAIDS syndrome.