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Specific human astrocyte subtype revealed by affinity purified GFAP antibody; unpurified serum cross-reacts with neurofilament-L in Alzheimer
Middeldorp J, van den Berge SA, Aronica E, Speijer D, Hol EM.. PloS one, 2009-11-04
Topic: Brain proteins, microglia and lab models
The human GFAP splice variants GFAPDelta164 and GFAPDeltaexon6 both result in a GFAP protein isoform with a unique out-of-frame carboxy-terminus that can be detected by the GFAP+1 antibody. We previously reported that GFAP+1 was expressed in astrocytes and in degenerating neurons in Alzheimer's disease brains. In this study we aimed at further investigating the neuronal GFAP+1 expression and we started by affinity purifying the GFAP+1 antibody. The purified antibody resulted in a loss of neuronal GFAP+1 signal, although other antibodies directed against the amino- and carboxy-terminus of GFAPalpha still revealed GFAP-immunopositive neurons, as described before. With an in-depth analysis of a western blot, followed by mass spectrometry we discovered that the previously detected neuronal GFAP+1 expression was due to cross-reactivity of the antibody with neurofilament-L (NF-L). This was confirmed by double-label fluorescent immunohistochemistry and western blotting with the unpurified GFAP+1 antibody and an antibody against NF-L. Our data imply that NF-L can accumulate in some tangle-like structures in Alzheimer brains. More importantly, the purified GFAP+1 antibody clearly revealed a specific subtype of astrocytes in the adult human brain. These large astrocytes are present throughout the brain, e.g., along the subventricular zone, in the hippocampus, in the striatum and in the spinal cord of controls, Alzheimer, and Parkinson patients. The presence of a specific GFAP-isoform suggests a specialized function of these astrocytes.
Key findings
- The human GFAP splice variants GFAPDelta164 and GFAPDeltaexon6 both result in a GFAP protein isoform with a unique out-of-frame carboxy-terminus that can be detected by the GFAP+1 antibody.
- The purified antibody resulted in a loss of neuronal GFAP+1 signal, although other antibodies directed against the amino- and carboxy-terminus of GFAPalpha still revealed GFAP-immunopositive neurons, as described before.
- More importantly, the purified GFAP+1 antibody clearly revealed a specific subtype of astrocytes in the adult human brain.
Why it matters
This study found that an antibody previously thought to detect a GFAP form in neurons was actually cross-reacting with neurofilament-L, and a purified version revealed a specific astrocyte subtype in human brain. It is a laboratory methods study and does not test any treatment, cure, or prevention for Alzheimer's disease.
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Study details
- Evidence strengthLow
How this study scored 41/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (PloS one) |
| Journal's citation record | 4 / 4 | PLoS ONE: journal h-index 594 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 1 / 5 | 2009 — within 20 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 3 / 7 | Cited 31 times (OpenAlex, 2026-10-10) |
| Citations per year | 1 / 5 | 1.6 citations a year over 19 year(s) since 2009 |
| Impact for its field and year | 2 / 6 | Cited 2.2× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 1 / 6 | Cited by 2 other studies in this library |
| Still being cited | 1 / 4 | Cited 6 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 3 / 4 | Last-listed author Elly M. Hol: h-index 68 (OpenAlex, whole career) |
| Institution's track record | 1 / 3 | University of Amsterdam: institution h-index 1,209 (OpenAlex) |
| Multi-centre collaboration | 2 / 3 | OpenAlex lists 5 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 19888461) |
| Free to read | 2 / 2 | Free to read |
| Total | 41 / 100 | — |
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Read the original
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
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APA 7th
Middeldorp, J., van den Berge, S. A., Aronica, E., Speijer, D., & Hol, E. M. (2009). Specific human astrocyte subtype revealed by affinity purified GFAP antibody; unpurified serum cross-reacts with neurofilament-L in Alzheimer. PloS one. https://doi.org/10.1371/journal.pone.0007663
Vancouver
Middeldorp J, van den Berge SA, Aronica E, Speijer D, Hol EM. Specific human astrocyte subtype revealed by affinity purified GFAP antibody; unpurified serum cross-reacts with neurofilament-L in Alzheimer. PloS one. 2009. doi:10.1371/journal.pone.0007663. PMID: 19888461.
BibTeX
@article{middeldorp2009-19888461,
author = {Middeldorp, J. and van den Berge, S. A. and Aronica, E. and Speijer, D. and Hol, E. M.},
title = {{Specific human astrocyte subtype revealed by affinity purified GFAP antibody; unpurified serum cross-reacts with neurofilament-L in Alzheimer}},
journal = {PloS one},
year = {2009},
doi = {10.1371/journal.pone.0007663},
pmid = {19888461},
url = {https://doi.org/10.1371/journal.pone.0007663}
}
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