Intracellular cAMP may inhibit T cell activation and proliferation via activation of the cAMP-dependent protein kinase, PKA. PKA signaling is maintained through interactions of the regulatory subunit with A-kinase anchoring proteins (AKAPs). We demonstrated that T cells contain AKAPs and now ask whether PKA anchoring to AKAPs via the RIIα regulatory subunit is necessary for cAMP-mediated inhibition of T cell activation. We studied the immune systems of mice lacking the RIIα regulatory subunit of PKA (-/-) and the ability of cells isolated from these mice to respond to cAMP. Dissection of spleen and thymus from wild-type (WT) and -/- mice, single cell suspensions generated from these organs, and iow cytometry analysis illustrate that the gross morphology, cell numbers, and cell populations in the spleen and thymus of the -/- mice are similar to WT controls. In vitro, splenocytes from -/- mice respond to anti-CD3/anti-CD28 and PMA/ionomycin stimulation and produce IL-2 similar to WT. Cytokine analysis revealed no significant difference in Th1 or Th2 differentiation. Finally, equivalent frequencies of CD8+ IFN-γ producing effector cells were stimulated upon infection of WT or -/- mice with Listeria monocytogenes. These data represent the first study of the role of RIIα in the immune system in vivo and provide evidence that T cell development, homeostasis. and the generation of a cell-mediated immune response are not altered in the RIIa -/- mice, suggesting either that RIIα is not required for normal immune function or that other proteins are able to compensate for RIIa function.
ASJC Scopus subject areas
- Immunology and Allergy