The Journal of Immunology, 1968, 100: 604-611.
Copyright © 1968 by The American Association of Immunologists, Inc.
Direct Demonstration and Quantitation of Aal, Aa2 and Aa3 Allotypic Specificities on Fd-Fragments of Rabbit Immunoglobulin G
Antoine Micheli1,
Rose G. Mage and
Ralph A. Reisfeld
From the Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
Abstract
- 1. Fd-fragments were prepared from Fab-fragments obtained by papain digestion of rabbit immunoglobulin-G (IgG). In addition, a 5 S piece was obtained by cyanogen bromide treatment of IgG and an Fd derived from the 5 S piece was prepared.
- 2. Polyalanylation was carried out in order to solubilize the Fd-fragments. Some masking of a-locus-allotypic specificity was demonstrated when IgG and 5 S piece were polyalanylated.
- 3. 125I-labeled fragments were allowed to react with either anti-a1, -a2 or -a3 antisera and supernatant portions were precipitated with appropriate anti-allotype antisera specific only for the antibody portion of the soluble complexes. In spite of some probable masking due to polyalanylation, the majority of polyalanylated Fdfragments (generally more than 60%) had demonstrable determinants associated with a-locus-allotypic specificity.
- 4. Fab-fragment (a2), from which noncovalently linked glycopeptides were removed on Sephadex in 1 M propionic acid, retained a2 allotypic specificity.
- 5. Fd-fragments derived from CNBr treated IgG, especially those with short polyalanine chains, gave high control values with normal rabbit sera, suggesting either a nonspecific or a specific affinity for immunoglobulins in normal rabbit sera.
Footnotes
1 Present address: Institut de Biochimie, 21 rue du Bugnon, Lausanne, Switzerland.
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