Histamine, neutrophil chemotactic factor and circulating basophil levels following exercise in asthmatic and control subjects.

Significant increase in the maximum post-exercise values of plasma histamine (PH), whole blood histamine (WBH) and neutrophil chemotactic factor (NCF) occurred in arterial blood within the first hour after exercise in asthmatic patients. However, similar changes in PH and WBH also occurred in the control group. Significant increases in circulating basophil counts following exercise were found in both groups, which closely mirrored the changes in PH and NCF, and there was a highly significant correlation between rises in WBH and basophil counts (P less than 0.001). When plasma histamine as assayed in venous blood using a more sensitive and specific double isotope radio enzymatic assay no significant alteration in plasma histamine levels was detected in either the asthmatic or the control group. We conclude that there is no evidence from these studies to support the suggestion that mast cell mediator release is involved in the pathogenesis of exercise-induced asthma, and that any observed changes in levels of PH and NCF after exercise may be related to changes in levels of circulating basophils.