Erythrocyte acid phosphatase in human hair root sheaths.

Erythrocyte acid phosphatase (EAP) was observed in human hair root sheaths where hair sheaths and blood samples were collected from 150 donors. In each case, the hairs were typed first for EAP and then confirmed by typing the blood from the same donors. Of the 150 donors checked, EAP activity was found in 135 of the samples; the other 15 samples showed no activity because they contained no sheath cells. Of the 135 samples showing activity, 108 of those were typed accurately in EAP. The remaining 27 samples had EAP activity but with inconclusive findings. In this study, all six common phenotypes were encountered.