CD44 expression in human meningiomas: An immunocytochemical, immunohistochemical and flow cytometric analysis

CD44 is a polymorphic family of cell adhesion molecules that has been impli cated in tumour invasion and metastasis. In this comparative analysis study , we investigated the expression of the standard form of CD44 (CD44s or CD4 4H) in 25 early passage cultures of meningiomas and histological sections, using immunohistochemical, immunocytochemical and flow cytometry techniques . There were 20 grade I, 3 grade II and 2 grade III meningiomas in the stud y which also included 2 recurrent meningiomas and meningioma arising some t ime after previous radiotherapy. Immunocytochemistry and flow cytometry res ults on early passage culture cells show that although the majority of the meningiomas were strongly positive for CD44H, some were only weakly positiv e. Immunohistochemical studies revealed a great variability in staining pat terns both within individual tumours and between different tumours. General ly, the intensity varied between strong and negative, and in most tumours t hat were immunopositive, there was a multifocal pattern of staining. Five m eningiomas did not stain at all for CD44H. Taken together, these findings s uggest that generally the flow cytometry results correspond well with those of both immunocytochemical and immunohistochemical techniques, with a few exceptions. It is concluded that microenvironmental factors may be responsi ble for the differential expression seen with different techniques.