Human basophil releasability. VIII. Increased basophil releasability in patients with scleroderma.

We evaluated basophil releasability in 16 female patients with scleroderma (systemic sclerosis) and in 16 normal age- and sex-matched donors. Basophils from patients with scleroderma released significantly more histamine "spontaneously" than did those from normal donors (12.9 +/- 2.1% versus 4.5 +/- 0.7%; P less than 0.0005). Basophil reactivity (maximal percentage histamine release) to anti-IgE was higher in patients with scleroderma than in controls (57.0 +/- 7.5% versus 35.4 +/- 7.8%; P less than 0.05). Basophil sensitivity (the concentration of anti-IgE that causes 40% of maximal percentage histamine release) to anti-IgE in scleroderma patients was similar to that found in controls (4.6 +/- 2.8 x 10(-2) micrograms/ml versus 2.3 +/- 1.0 x 10(-1) micrograms/ml; P not significant). Scleroderma patients also showed enhanced releasability compared with that of the controls when challenged in vitro with interleukin-3 (8.3 +/- 1.7% versus 3.2 +/- 0.6%; P less than 0.01). Releasability induced by the formyl-containing tripeptide, f-met peptide, was significantly higher in the scleroderma patients than in the controls at the 2 lower concentrations used. No differences in basophil reactivity and sensitivity to f-met peptide and calcium ionophore A23187 were found between patients and normal donors. These results show that spontaneous basophil releasability and releasability in response to IgE cross-linking and activation of interleukin-3 receptors are increased in patients with scleroderma.