Demonstration of IgM antibodies of high affinity within the anti-Galalpha1-3Gal antibody repertoire.
BACKGROUND
Human anti-Galalpha1-3Gal IgG and IgM xenoantibodies can distinguish between very similar epitopes with a high degree of selectivity.


METHODS
Anti-Galalpha1-3Gal antibodies were affinity isolated using two separate Galalpha1-3Gal-based immunoadsorbents, Galalpha1-3Gal itself and Galalpha1-3Galbeta1-4Glc. IgG and IgM were separated using a protein G column. Antibody purity was achieved by serial adsorption/elutions from the columns. By this means, different antibody fractions were prepared that contained either IgG or IgM, reactive with either Galalpha1-3Gal, Galalpha1-3Galbeta1-4Glc, or both. The dissociation equilibrium constants (Kd) of these antibodies were then measured using an IAsys biosensor.


CONCLUSIONS
Sera from two individuals were used and Kd values for one IgG (fraction 1A) and two IgM (fractions 1B and 2A) fractions were obtained. The Kd for the IgG was 4.85 x 10(-7) M (fraction 1A). For IgM, the Kd values were higher at 7.8x10(-10) M (fraction 1B) and 1.07x10(-10) M (fraction 2A). Natural anti-pig antibodies include high affinity IgM that continue to be produced without class switch. The B cell mechanism behind this is not known. It may be possible to exploit this mechanism in future xenotransplantation strategies.
Lee
J
J
The Brent Laboratory, St. Mary's Hospital, London, England, United Kingdom.
Cairns
T
T
McKane
W
W
Rashid
M
M
George
A J
AJ
Taube
D
D
D000906:Antibodies / Q000032:analysis / Q000276:immunology*; D000915:Antibody Affinity / Q000276:immunology; D004187:Disaccharides / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis / Q000276:immunology*; D007163:Immunosorbent Techniques
D000906:Antibodies; D004187:Disaccharides; D007074:Immunoglobulin G; D007075:Immunoglobulin M