Vimentin and glial fibrillary acidic protein expression in relation to neoplastic cell differentiation in glial tumors.

In the present work the expression of vimentin and glial fibrillary acidic protein (GFAP) was determined in homotypic, transitional and heterotypic astroglial neoplastic areas and gemistocytes. The expression of these intermediate filament (IF) proteins within oligodendroglial neoplastic cells was determined as well. The intensity of vimentin and GFAP immunoreactivity as well as the number of immunoreactive cells within astroglial areas of different grades of differentiation were different. While there was no immunoreactivity within heterotypic areas, transitional areas and gemistocytes mainly show the same intensity of immunoreactivity and number of immunoreactive cells for both analyzed IF proteins. Within homotypic astroglial areas the number of GFAP positive cells and intensity of GFAP immunoreactivity were higher than the same vimentin parameters. It is well known that vimentin and GFAP may form heteropolymers both in vitro and in vivo. Transitions in vimentin/GFAP expression reflect not only normal development of astroglial cells but occur also with the induction of neoplastic process. Our results suggest that immunoreaction intensity and number of vimentin or GFAP immunoreactive cells correlates with the degree of differentiation of specific neoplastic cell populations. It is suggested that transitions in vimentin and GFAP expression occur in the course of neoplastic progression presumably by the modulation of their incorporation into the same IF system according to the degree of neoplastic cell differentiation.