The determination of blood histamine in asthmatic patients with a simple and sensitive method.

The histamine level of whole blood and plasma in asthmatic patients was estimated by means of a simple, sensitive and specific method, which was developed to measure low histamine levels. This method consists of the following procedures; the partial purification of histamine with a small P-cellulose column; its further purification with high performance liquid chromatography (HPLC); and fluorometric detection with precolumn o-phthaldehyde (OPT) reaction. The present assay could detect as little as 0.5 ng of histamine concentration. Blood histamine levels in patient with asthmatic attack, 57 +/- 34 ng/ml (mean +/- S.D. N = 14), were significantly different from those in symptom-free period, 37 +/- 15 ng/ml (N = 15) as well as those in normal subjects, 36 +/- 17 ng/ml (N = 12). However, there were no significant differences among plasma histamine levels in normal subjects, 1.6 +/- 1.7 ng/ml (N = 12) and, in asthmatic patients during attacks, 1.6 +/- 1.8 ng/ml (N = 14) and symptom-free periods, 1.6 +/- 1.7 ng/ml (N = 15). These results indicate that plasma histamine concentration does not increase during asthmatic attacks, even though there was significant increase of blood histamine concentration.