By phage display, llama-derived heavy chain antibody fragments were selected from non-immune and immune libraries and tested for their affinity and specificity for beta amyloid by phage-ELISA,... Show moreBy phage display, llama-derived heavy chain antibody fragments were selected from non-immune and immune libraries and tested for their affinity and specificity for beta amyloid by phage-ELISA, immunohistochemistry and surface plasmon resonance. We identified eight distinct heavy chain antibody fragments specific for beta amyloid. While three of them recognized vascular and parenchymal beta amyloid deposits, the remaining five heavy chain antibody fragments recognized vascular beta amyloid specifically, failing to bind to parenchymal beta amyloid. These heavy chain antibody fragments, selected from different libraries, demonstrated differential affinity for different epitopes when used for immunohistochemistry. These observations indicate that the llama heavy chain antibody fragments are the first immunologic probes with the ability to differentiate between parenchymal and vascular beta amyloid aggregates. This indicates that vascular and parenchymal beta amyloid deposits are heterogeneous in epitope presence/availability. The properties of these heavy chain antibody fragments make them potential candidates for use in in vivo differential diagnosis of Alzheimer disease and cerebral amyloid angiopathy. Continued use and characterization of these reagents will be necessary to fully understand the performance of these immunoreagents. (C) 2009 Elsevier Inc. All rights reserved. Show less
Rutgers, K.S.; Nabuurs, R.J.A.; Berg, S.A.A. van den; Schenk, G.J.; Rotman, M.; Verrips, C.T.; ... ; Maarel, S.M. van der 2011
Previously selected amyloid beta recognizing heavy chain antibody fragments (VHH) affinity binders derived from the Came lid heavy chain antibody repertoire were tested for their propensity to... Show morePreviously selected amyloid beta recognizing heavy chain antibody fragments (VHH) affinity binders derived from the Came lid heavy chain antibody repertoire were tested for their propensity to cross the blood-brain barrier (BBB) using an established in vitro BBB co-culture system. Of all tested VHH, ni3A showed highest transmigration efficiency which is, in part, facilitated by a three amino acid substitutions in its N-terminal domain. Additional studies indicated that the mechanism of transcellular passage of ni3A is by active transport. As VHH ni3A combines the ability to recognize amyloid beta and to cross the BBB, it has potential as a tool for non-invasive in vivo imaging and as efficient local drug targeting moiety in patients suffering from cerebral amyloidosis such as Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved. Show less
