[Phospholipase A2 activating factor in sera of patients with psoriasis vulgaris].

Phospholipase A2 (PL-A2) has been known to be activated in either affected or un-affected skin of patients with psoriasis vulgaris. The present study was designated to investigate whether or not there is a factor activating PL-A2 in their sera, using cultured murine epidermal cells (NCTC-2544). The cultured cells prelabeled with 3H-arachidonic acid (3H-AA). After adding a serum, the release of 3H-AA into medium from the cells was measured. The sera from 20 patients with psoriasis vulgaris showed significantly increased releases of 3H-AA as compared with those by sera from 10 healthy individuals, indicating that there may be a PL-A2 activating factor in the sera of psoriasis vulgaris. The PL-A2 activating factor in the patient sera was not inactivated with added 2 different PL-A2 inhibitors. The sera were not able to produce 3H-AA from 3H-AA labeled phospholipids. Therefore, PL-A2 activating factor does not seem to be PL-A2 itself existing in the sera. Through heat stability, dialysis, and fractionation studies, the PL-A2 activating factor in sera was found to be a protein, which had a molecular weight of more than 50 kd and was stable at 56 degrees C.