Immunohistochemical analysis of intermediate filament (IF)
proteins was performed on frozen sections of 16 childhood glial
tumors using a library of 10
antigen-specific IF
protein directed
monoclonal antibodies (MoABs) and a four-step
biotin-
streptavidin-
alkaline phosphatase conjugated
antigen detection immunocytochemical technique. Human
glial fibrillary acidic protein (GFAP) and
vimentin were expressed in all
brain tumors. High molecular weight (200 kDa)
neurofilament (NF-H) protein was expressed in 15 out of 16
tumors; medium molecular weight (160 kDa) neurofilament (NF-M) in seven out of 16
tumors; and low molecular weight (68 kDa) neurofilament (NF-L) in five out of 16. Positive acidic
keratin reactivity was found in five out of 16
tumors using MoAB AE1. Expression of a
keratin pair was detected with MoAB AE2 in five out of 16
tumors. A second
keratin pair in 14 out of 16 glial
tumors was demonstrated with MoAB AE3. Immunostaining with AE5 defined the expression of another basic
keratin (64 kDa) in nine out of 16 glial
tumors. Finally, in 14 out of 16
astrocytomas an individual 51 kDa acidic
keratin (detected with MoAB AE8) was expressed. Glial
tumor cells contain cell lineage specific and nonspecific IF
proteins in the following IF pattern: AE3+, AE8+, GFAP+,
vimentin+, and NF-H+. The heterogenous composition of these cytoskeletal IF
proteins in childhood glial
tumors may reflect a direct stage dependent correlation with their neoplastic transformation.