Neurofilament-like pattern of reactivity in human foetal PNS and spinal cord following immunostaining with polyclonal anti-glial fibrillary acidic protein antibodies.

The intermediate filament protein, glial fibrillary acidic protein (GFAP), is widely used as a cell-specific marker molecule for immunocytochemical identification of astrocyte lineages in cell culture, in tissues during development, and in tissues undergoing pathological changes. This study demonstrates that a reaction pattern of two commercially available polyclonal anti-GFAP antibodies shows extensive similarity to the pattern of reactivity obtained with monoclonal antibodies to neurofilaments in the PNS and spinal cord of human embryos and foetuses, at 5 to 12 weeks of gestation. The polyclonal antibodies to GFAP labelled populations of neurons and their processes in the PNS and in the spinal cord. Monoclonal antibodies to GFAP only labelled glial cells in the spinal cord. Neurofilament adsorption of one of the anti-GFAP antisera abolished the neurofilament-like reaction pattern, while the structures also labelled with monoclonal antibodies to GFAP remained immunostained. The results presented may question previously published data obtained with these and possibly other polyclonal anti-GFAP antibodies.