RADIATION-INDUCED MEMBRANE-CHANGES AND PROGRAMMED CELL-DEATH - POSSIBLE INTERRELATIONSHIPS

A short review of the evidence that lymphocyte membranes are a target for the initiation of irradiation induced programmed cell death (PCD) is given. It is assumed that for lymphocytes PCD represents an essenti al physiological mechanism in order to prevent degeneration of the bio logical system involved. Initiation of PCD can be obtained by a pharma cological activation as well as with irradiation. In both cases, prote in kinase-C (PKC) is involved in the signal transduction from the cell ular membrane to the nucleus where, by means of a metabolically active process, DNA fragmentation is induced. It is hypothesized that proces ses connected to lipid peroxidation in the cell membrane constitute a primary effect of irradiation induced PCD, where membrane fluidization or a compensatory process aimed to the maintenance of membrane fluidi ty (membrane homeoviscosity hypothesis) are likely to be involved.