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Developmental Immunology
Volume 3 (1992), Issue 1, Pages 67-84

Serum Amyloid P Component (SAP)-Like Protein From Botryllid Ascidians Provides a Clue to Amyloid Function

1Department of Biology, UCLA School of Medicine, Los Angeles, California 90024, USA
2Department of Microbiology, University of Arizona College of Medicine, Tucson, Arizona 85724, USA
3Sir William Dunn School of Pathology, Oxford University, South Parks Rd., Oxford OX1 3RE, UK

Received 25 July 1991; Accepted 12 February 1992

Copyright © 1992 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The HA-1 lectin isolated from Botrylloides leachii has an amino acid composition similar to that of mammalian serum amyloid protein (SAP). SAP is a universal component of mammalian amyloid deposits. Like SAP, HA-1 has a disc ultrastructure, and antibody to HA-1 binds both (a) to amyloidlike fibers deposited between rejected Botrylloides colonies and (b) to cerebral amyloid deposits in Alzheimer's disease brains. Deposition of protochordate amyloid within rejection sites and surrounding fouling organisms implies that these fibers function as barriers to allogeneic and infectious challenge. Similarly, mammalian amyloid may also function to contain inflammatory lesions and to limit the spread of certain infections. Pathological amyloidotic conditions in humans, such as Alzheimer's disease, may result from unregulated expression of this primitive encapsulation response.