Increased Activation of Protein Kinase A Type I Contributes to the T Cell Deficiency in Common Variable Immunodeficiency
The molecular mechanisms underlying the T cell dysfunction often present in common variable immunodeficiency (CVI) are not established. cAMP-dependent protein kinase A type I (PKAI) is an important inhibitor of T cell proliferation after Ag stimulation. We therefore investigated the possibility that...
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Published in | The Journal of immunology (1950) Vol. 162; no. 2; pp. 1178 - 1185 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Am Assoc Immnol
15.01.1999
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Subjects | |
Online Access | Get full text |
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Summary: | The molecular mechanisms underlying the T cell dysfunction often present in common variable immunodeficiency (CVI) are not established. cAMP-dependent protein kinase A type I (PKAI) is an important inhibitor of T cell proliferation after Ag stimulation. We therefore investigated the possibility that activation of PKAI may be involved in the development of T cell dysfunction in CVI. An exogenously added PKAI-selective antagonist (Rp-8-Br-cAMPS) induced a significant increase in anti-CD3-stimulated PBMC proliferation in 20 CVI patients compared with no effect in 15 controls. Purified T cells from 7 CVI patients with strictly defined T cell deficiency had elevated endogenous cAMP levels compared with controls. Treatment of T cells from these CVI patients with Rp-8-bromo-cAMP-phosphorothioate markedly improved anti-CD3-stimulated proliferation (up to 3.7-fold), particularly in CD4+ lymphocytes, reaching proliferation levels comparable to control values. No effect of cAMP antagonist on T cell proliferation was seen in controls. In these CVI patients, cAMP antagonist also increased IL-2 production in anti-CD3-stimulated T cells. However, exogenously added IL-2 at concentrations comparable to the achieved increase in IL-2 levels after addition of cAMP antagonist had no effect on T cell proliferation. Furthermore, the stimulatory effects of exogenously added IL-2 at higher concentrations and cAMP antagonist on T cell proliferation were additive. Our findings indicate that increased PKAI activation may be an important molecular basis for the T cell defect in CVI and suggest that the cAMP/PKAI system may be a potential molecular target for immunomodulating therapy in these patients. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0022-1767 1550-6606 |
DOI: | 10.4049/jimmunol.162.2.1178 |