TY - JOUR
T1 - Immunochemical characterization of the distinct monocyte cyclic AMP-phosphodiesterase from patients with atopic dermatitis
AU - Chan, Sai C.
AU - Reifsnyder, David
AU - Beavo, Joseph A.
AU - Hanifin, Jon M.
PY - 1993/6
Y1 - 1993/6
N2 - Background: Previous findings have suggested that the immunopathology of patients with atopic dermatitis (AD) results from altered cellular responses caused by cyclic nucleotide regulatory abnormalities. One such defect is the increased degradation of the second messenger, cyclic adenosine monophosphate (cAMP), by elevated cAMP-phosphodiesterase (PDE) activity in patients with AD. Methods: We used two monoclonal antibodies to identify the major PDE isoform in AD blood monocytes. We have also characterized the abnormal PDE activity by means of chromatofocusing and sucrose gradient centrifugation. Results: The chromatofocusing technique allowed the separation of a PDE-containing fraction (isoelectric point = 6.1) from AD monocytes but not from normal cells. This monocyte fraction accounted for most of the elevated leukocyte-PDE activity and was a cytosolic, cAMP-specific, low Michaelis constant, calcium-calmodulin-dependent enzyme, inhibited by the cAMP-PDE inhibitor, Ro 20-1724. The majority of the PDE activity in this chromatofocused fraction was immunoadsorbed by the solid-phase immobilized antibodies against calcium-calmodulin-dependent PDE. Conclusions: The increased degradation of cAMP by a unique form of PDE may cause defective regulation of intracellular functions of AD monocytes, leading to the characteristic hyperreactive immune and inflammatory events. Characterization of PDE isoenzymes from different leukocyte subpopulations may allow further expansion of cell-directed therapy for inflammatory disease.
AB - Background: Previous findings have suggested that the immunopathology of patients with atopic dermatitis (AD) results from altered cellular responses caused by cyclic nucleotide regulatory abnormalities. One such defect is the increased degradation of the second messenger, cyclic adenosine monophosphate (cAMP), by elevated cAMP-phosphodiesterase (PDE) activity in patients with AD. Methods: We used two monoclonal antibodies to identify the major PDE isoform in AD blood monocytes. We have also characterized the abnormal PDE activity by means of chromatofocusing and sucrose gradient centrifugation. Results: The chromatofocusing technique allowed the separation of a PDE-containing fraction (isoelectric point = 6.1) from AD monocytes but not from normal cells. This monocyte fraction accounted for most of the elevated leukocyte-PDE activity and was a cytosolic, cAMP-specific, low Michaelis constant, calcium-calmodulin-dependent enzyme, inhibited by the cAMP-PDE inhibitor, Ro 20-1724. The majority of the PDE activity in this chromatofocused fraction was immunoadsorbed by the solid-phase immobilized antibodies against calcium-calmodulin-dependent PDE. Conclusions: The increased degradation of cAMP by a unique form of PDE may cause defective regulation of intracellular functions of AD monocytes, leading to the characteristic hyperreactive immune and inflammatory events. Characterization of PDE isoenzymes from different leukocyte subpopulations may allow further expansion of cell-directed therapy for inflammatory disease.
KW - Atopic dermatitis (AD)
KW - anti-PDE monoclonal antibodies
KW - chromatofocusing
KW - immunoadsorption
KW - mononuclear leukocytes (MNLs)
KW - phosphodiesterase (PDE)
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U2 - 10.1016/0091-6749(93)90321-6
DO - 10.1016/0091-6749(93)90321-6
M3 - Article
C2 - 8389777
AN - SCOPUS:0027194175
SN - 0091-6749
VL - 91
SP - 1179
EP - 1188
JO - The Journal of Allergy and Clinical Immunology
JF - The Journal of Allergy and Clinical Immunology
IS - 6
ER -