Immunoglobulin G; Lectins; Peanut Agglutinin; Pokeweed Mitogens; Concanavalin A
Abstract :
[en] A solid phase radioimmunoassay was set up for direct measurement of the binding
capacity of human IgG to three lectins recognizing different carbohydrates of the
Fc domain, i.e. peanut agglutinin (PNA), Concanavalin A (Con A) and pokeweed
mitogen (PWM) which mainly bind to beta-galactose, alpha-mannose and dimers of
N-acetyl-beta-glucosamine respectively. The mean specific binding of the 96
normal IgG tested to PNA and to PWM was statistically higher (P less than 0.001)
than that to Con A, whereas no significant differences were observed between the
mean specific bindings to PNA and to PWM. A statistically significant linear
negative correlation could be established only between the relative bindings
(expressed in percentage of the total binding to the three lectins) to PNA and to
PWM (r = -0.65, P less than 0.001). The mean specific binding of IgG purified
from 34 patients suffering from rheumatoid arthritis (RA) to PNA and to Con A was
statistically higher (P less than 0.001) than that reached with PWM, whereas no
significant differences were noted between their mean binding capacities to PNA
and to Con A. When compared to normal IgG, only four out of 34 RA IgG exhibited a
significantly higher binding capacity to PNA, whereas all but one RA IgG
possessed a significantly higher binding capacity to Con A. Accordingly, the mean
specific binding of RA IgG to Con A was significantly higher than that of normal
IgG (P less than 0.001). Besides (and contrary to normal IgG), a statistically
significant negative linear correlation was noted between the relative bindings
of RA IgG to PNA and to Con A (r = -0.89, P less than 0.001). All the five RA IgG
tested exhibited an abnormal circular dichroism. Our data suggest that, by
altered steric conformation and glycosylation, mannosyl-residues of RA IgG become
prominent or terminal or both, and are therefore able to react more effectively
with Con A than normal IgG do.
Disciplines :
Rheumatology
Author, co-author :
Malaise, Michel ; Université de Liège - ULiège > Département des sciences cliniques > Rhumatologie
Franchimont, P.
Bouillene, C.
Houssier, C.
Mahieu, P. R.
Language :
English
Title :
Increased concanavalin A-binding capacity of immunoglobulin G purified from sera of patients with rheumatoid arthritis
