THE RELATIONSHIP OF KI67 AND INVOLUCRIN EXPRESSION IN PROLIFERATIVE, PRENEOPLASTIC AND NEOPLASTIC SKIN

In normal skin, proliferation and differentiation are tightly coupled in order to maintain normal architecture in a continually renewing tis sue. The temporal and spatial relationships between these two processe s in normal, psoriatic, pre-neoplastic and neoplastic skin were invest igated by a double immunolabelling technique with Ki67 as a marker of proliferation and involucrin as a marker of terminal differentiation. In normal shin, expression of the two antigens was strictly spatially segregated. In the abnormal, the proportions of cells expressing the a ntigens were increased with some loss of the spatial segregation, whil e small numbers of cells showed dual expression suggesting loss of the normal control between proliferation and differentiation. However, th e quantitative ratio of proliferation to differentiation in psoriatic and pre-neoplastic skin was similar to the normal; transition to an in vasive phenotype, however, was associated with a reversal of this rati o, and this correlated well with the degree of histological differenti ation.