Histamine-releasing activity and bronchoconstricting effects of sisal.

142-145. Extracts of dry and oiled sisal released histamine from pig and human but not from rat lung tissue. A suspension in Tyrode solution of the oil used for softening the sisal fibres had a pH of 8·1 and also released histamine from pig and human lung. The releasing activity was abolished when the pH of this suspension was adjusted to pH 7·4. As all the sisal extracts were adjusted to pH 7·4 for incubation with lung tissue, the histamine-releasing activity of sisal is unrelated to the presence of the oil. Significant (P < 0·01) mean reductions over the work shift of ventilatory capacity (PEF and FEV) were recorded in all the workers exposed to airborne sisal dust. These reductions were greater in combers than in drawers and spinners. Sisal collected from combing machines possessed more histamine-releasing activity than material from drawing and spinning machines. These results indicate that histamine release by sisal may be the cause of acute ventilatory capacity changes in sisal exposure.