On the histamine‐binding property of human serum

In 1968, Gecse, Kartidy & West reported that a non-protein fraction of rat serum and of human serum contains a substance which has the power in vitro to bind histamine. The active material was considered to be polypeptide in nature, with a molecular weight between 1000 and 5000. This finding was at variance with that of Guirgis (1967) who stated that the histamine-binding activity of human serum was in the relatively small molecular weight protein fraction which was linked in some way with both albumin and uand P-globulins. We now report that the histaininebinding substance in human serum is attached predominantly to albumin from which it splits off during the process of coagulation or after papain digestion. Of even greater importance is the finding that serum from allergic patients lacks this histamine-binding property. In our studies, blood was withdrawn from 30 healthy human volunteers (15 men and 15 women, aged 18-40 years) into glass tubes without anticoagulant. It was left at room temperature for 1 h to initiate coagulation and then warmed to 37" for another h to complete clot retraction. Serum was then obtained by centrifugation at 5000 g for 30 min at 0". Serum (1 ml) was transferred to a Sephadex G 25 column (diameter 1 cm, length 47 cm) and this was eluted with a solution of sodium chloride (0.lh.1, pH 6.7, temperature 4") passing at a rate of 10 ml/h. The eluate was collected in 1.5 in1 samples and each was tested both for protein using agarose gel electrophoresis, the ninhydrin reaction, and light absorption at 280 nm, and for polypeptides by thin-layer chromatography, the ninhydrin reaction and amino-group halogenization with iodine vapour. After a dead space of about 15 ml (samples 1-10), the serum proteins were detected in the next 9 ml (samples 11-16). The next 4 samples were free of nitrogenous material (see Fig. 1) but polypeptides of low molecular weight (between 1000 and 5000) were eluted in the next 9 ml (samples 21-26), their peak concentration, as measured by the intensity of the ninhydrin reaction using light absorption at 510 nm, being at sample No. 23 (that is, after 35 ml of eluate had been collected).