Incontinentia pigmenti: eosinophil chemotactic activity of the crusted scales in the vesiculobullous stage.

To investigate the mechanisms underlying eosinophil infiltration into the epidermis in incontinentia pigmenti (IP), we studied the eosinophil chemotactic activity in extracts of the crusted scales from three patients with IP in the vesiculobullous stage. Eosinophil chemotactic activity was detected in the eluates from a Sephadex G-75 chromatography column between the vitamin B12 and phenol red markers. The chemotactic activity was heat-stable and resistant to enzyme digestion, and recovered after ether extraction at low pH. Leukotriene B4 (LTB4) was demonstrated in the fractions with high eosinophil chemotactic activity. These findings suggest that LTB4 plays an important role in the accumulation of eosinophils within the epidermis in IP, in the vesiculobullous stage. Blood eosinophilia, however, may not be induced by the eosinophil chemotactic factors in the scales.