Serum levels of soluble CD14 in allergic inflammation

Monocytes/macrophages have recently been shown to play a significant role in the pathogenesis of allergic diseases. As the level of soluble CD14 (sCD14) in serum is considered a marker of monocyte/macrophage activation, we measured the levels of sCD14 in allergic asthma and atopic dermatitis (AD), along with acute infectious and inflammatory diseases, to see its clinical relevance. Serum samples were taken from patients with acute infectious and inflammatory diseases, allergic asthma, and atopic dermatitis. sCD14 was measured with our own ELISA system and its level in each disease was compared with normal controls as well as its disease severity. sCD14 was elevated and correlated with C-reactive protein in infectious and inflammatory diseases (n = 26), confirming that it reflects inflammation. sCD14 was also significantly increased both in asthma (n = 94) and adult chronic AD (n = 22). In asthmatic patients, those with higher sCD14 tended to have more severe symptoms, but there was no statistical correlation between sCD14 and severity. In adult chronic AD patients, a correlation between sCD14 and disease severity was observed. However, sCD14 was not elevated in infant AD patients (n = 18) irrespective of severity, suggesting differences in the degree of monocyte/macrophage involvement in the pathogenesis between adult chronic and infant AD. The levels of sCD14 were shown to be upregulated in allergic diseases and might be useful as a marker of monocyte/macrophage involvement in allergic inflammation.