Skin histamine in chronic urticaria

Abstract

To further study the role of histamine in the pathogenesis of chronic urticaria, the concentration of histamine in tissue extracts from skin biopsy samples and in plasma from patients with chronic urticaria was measured by a sensitive radioenzymatic assay. Tissue histamine levels from urticarial lesions and uninvolved skin were compared with extracts of biopsy samples taken from normal controls. The average tissue histamine content in 15 biopsy samples from the chronic urticaria patients was significantly higher than in those of 15 normal controls. Forty percent of the patients had levels 2 SD greater than the mean of the control group. Elevated histamine levels were also found in biopsy samples of uninvolved skin from some urticaria patients. Circulating histamine levels from chronic urticaria patients were rarely elevated and did not correlate with skin concentration. No correlation was noted between tissue histamine concentration and estimated mast cell concentration on Giemsa-stained sections of five biopsy samples. These results indicate that tissue histamine levels are increased in some patients with chronic urticaria. This suggests that local histamine elevations may be important in the pathogenesis of many patients with this disease. In addition, increased tissue histamine in these patients is not reflected by elevated circulating levels.