A subset of chronic lymphocytic leukemia (CLL) B cell receptors (BCRs) interact with antigens expressed on apoptotic cells, suggesting that CLL BCRs have the potential to internalize apoptotic cell RNA or DNA-containing fragments with resultant activation of TLR7 or TLR9, respectively. By blocking cAMP degradation, type 4 cyclic nucleotide phosphodiesterase (PDE4) inhibitors activate cAMP-mediated signaling and induce apoptosis in CLL cells. Here we show that autologous irradiated leukemic cells induce proliferation in CLL cells and that such proliferation is blocked by a TLR7/8/9 inhibitor, by DNase and by the PDE4 inhibitor rolipram. Rolipram also inhibited CLL cell proliferation induced by synthetic TLR7 and TLR9 agonists, as well as TLR agonist-induced costimulatory molecule expression and TNF-α (but not IL-6 or IL-10) production. While treatment with a TLR9 agonist protected immunoglobulin heavy chain variable region (IGHV) unmutated, but not mutated, CLL cells from apoptosis, PDE4 inhibitors augmented apoptosis in both subtypes, suggesting that cAMP-mediated signaling may abrogate a TLR9-mediated survival signal in prognostically unfavorable IGHV-unmutated CLL cells. Rolipram inhibited both TLR7/8 and TLR9-induced IRF5 and NF-κB p65 nuclear translocation. PDE4 inhibitors also blocked TLR signaling in normal human immune cells. In peripheral blood whole mononuclear cells (PBMC) and CD14-positive monocytes, PDE4 inhibitors blocked IFN-α or TNF-α (but not IL-6) production, respectively, following stimulation with synthetic TLR agonists or RNA-containing immune complexes. These results suggest that PDE4 inhibitors may be of clinical utility in CLL or autoimmune diseases that are driven by TLR-mediated signaling.