Immunomorphological analysis of the vascular stroma in glioblastoma]

The aim of the study was to characterize vascular stroma in glioblastoma (GB), to analyze its immunomorphological features, and to seek a relationship between patients' age and characteristics of the tumor microcirculation. Subjects in the study were 38 patients with GB, divided into two groups according to their age: group I--14 patients aged under 49 (from 32 to 49), and group II--24 patients over 50 years of age (51-78). Main types of vessels were specified: microvessels with normal morphology (capillaries, arterioles/venules), telangiectases, haemangioma--like forms, and microvascular proliferation types--simple and glomeruloid. An immunohistochemical analysis of the vascular stroma was performed with monoclonal antibodies against vWf and CD31, ASM, and Collagen IV (DAKO) to visualize the vessel wall components. The immunomorphological analysis was carried out for particular types of vessels separately. The vWf and ASM expression ratios--percentage of immunopositive area on 10 representative tumor fields under 100 x HPF--were assessed using a computer image analyzer. The incidence of some vessel types was dependent on the patients' age: in group I vascular--rich areas were more numerous, while in group II glomeruloid proliferation was more frequent--20/24-83.3% vs 8/14-57.1%. Immunoreactivity of the examined antigens was not related to the patients' age. The endothelial markers positivity was found within cells directly around the vascular lumen, and the reaction with vWf was more pronounced than CD31 reactivity. The most intense reactions were noted in proliferative changes of both types and in capillaries. ASM reactivity was found in abluminal cells within all types of vessels, most abundant in glomeruloid proliferation. ASM positivity was present also in some capillaries. Collagen IV staining revealed various abnormalities in the vascular basement membrane structure. No significant intergroup differences were found in the vWf and ASM expression ratios. However, in both groups the ASM expression ratio was significantly higher than that of vWf expression (p < 0.001).Expression of the vascular wall antigens under study depends on the blood vessel type. The number of cells with smooth muscle phenotype is significantly higher than that of endothelial cells, especially within proliferative vascular changes. Microvascular changes intensity is higher in the older patient group.