Inositol metabolism in mononuclear leucocytes from patients with atopic dermatitis.

Elevated activity of cyclic adenosine monophosphate-specific phosphodiesterase (PDE) has been previously documented in the peripheral blood mononuclear leucocytes (MNLs) of patients with atopic dermatitis (AD). Because of the potential interactions of the cyclic nucleotide and inositol secondary messenger systems we sought to determine whether differences exist in the inositol uptake and metabolism between atopic and normal MNLs. We found no difference in the uptake of tritiated inositol by MNL between 19 atopic patients and 16 non-atopic control subjects. However, after stimulation of MNLs by concanavalin A, there was a significantly greater metabolism of inositol to inositol-1-phosphate (IP1) in the controls compared to the atopic MNLs; the mean percentage rise in the IP1 fraction over baseline level was 40% in the atopics, but almost 200% in controls after 2 h. Diminished inositol metabolism in atopic MNLs may explain the reduced cell-mediated immunity that characterizes the atopic state.