Co-expression of four intermediate filament subclasses in childhood glial neoplasms

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.