Soluble Pityrosporum-derived chemoattractant for polymorphonuclear leukocytes of psoriatic patients.

The chemoattraction of polymorphonuclear leukocytes (PMNs) from psoriatic patients, atopic patients and healthy control persons by Pityrosporum orbicularelovale was investigated using the Boyden chamber method. The chemotactical attraction of PMNs from psoriatic patients by Pityrosporum (stimulation index SI = 58 +/- 50) was significantly increased (p < 0.05) compared to PMNs from atopic patients (SI = 20 +/- 17) and control persons (SI = 26 +/- 24). This effect seems to be specific for Pityrosporum, since the chemotactical response to Staphylococcus epidermidis was not increased in psoriasis. The chemotactical factor produced by Pityrosporum is hydrophilic and is destroyed by acid hydrolysis, indicating its protein nature. The yeast Pityrosporum may thus play a role in the koebnerization of psoriasis.