PAS-positive polymorphonuclear leucocytes in corneal ulcers.

Fifty consecutive cases of severe keratitis with clinical signs of corneal ulcers were examined histologically for stage of inflammatory reaction. Further, 14 similar cases were studied ultrastructurally. Cell counts of polymorphonuclears (PML), eosinophils, lymphocytes and plasma cells were carried out. Further the corneas were grouped according to their content of PAS-positive PML. The state of ulceration was estimated microscopically. PML at a cell count of greater than 10 cells/mean field (x 1000) were found in 32/50 cases, and were significantly more frequent in corneal areas with epithelial or Descemet membrane defects. Most PML were PAS-positive (26/50), the positive material having characteristics of glycogen. PAS-negative PML were found in corneas with increased amount of plasma cells. By TEM the PML were found highly phagocytic, partly degranulated and with reduced glycogen content. TEM could not, on the formalin fixed specimens, determine whether PAS-negative PML had a higher protein turn-over, but the findings indicate that corneal ulcers with PAS-negative PML contain a high amount of proteases, because of many degranulated PML and probably a reactivation of PML. Therefore the PAS stainability can be used as an indicator for the PML activity in corneal ulcers.