On the nature of IgG dimers. II. Idiotype--anti-idiotype complexes of polyclonal and monoclonal origin: size distribution patterns and molecular geometries.
Electron micrographs of a fraction containing dimers isolated from pooled human polyclonal immunoglobulin G (IgG) suggest essentially a cyclic geometry compatible with bivalently associated monomers. It is obvious that such a structure can be produced by idiotype (Id)--anti-idiotype (anti-Id) interactions where the latter are able to neutralize certain combining site related Id functions. Accordingly, antibody (ab) activities against tetanus toxoid (tt) and rubella antigen (ag) were found to be almost exclusively confined to the monomeric molecules in preparations composed of monomers and dimers only. Moreover, electron micrographs of complexes prepared from a murine monoclonal Id as well as anti-Id reveal the presence of ring complexes, especially of cyclic tetramers. Gel filtration patterns of mixtures containing equimolar concentrations (concns) of such abs (1.6 x 10(-6) M) show, correspondingly for 9 different Id--anti-Id pairs and therefore probably representing a more common feature, mainly the formation of even-numbered complexes, especially tetramers. That is basically in accordance to an equilibrium model developed by Archer and Krakauer but not from a quantitative point of view because non-ideality terms had not been originally included. Despite taking strain energies determined by Schumaker et al. for cyclic complexes of polyclonal rabbit abs and a bivalent hapten into account for computation of size distribution patterns, the predominant formation of dimers was, nevertheless, again predicted by the modified theory in contrast to the experimental results. Fundamental conformity could only be achieved by further decreasing one of the statistical factors, namely the ring closing factor, which theoretically influences the generation of cyclic dimers. Therefore, referring to the experimental results of Schumaker et al., we postulate a strain energy well above 700 cal/mol for cyclic dimers produced by interacting Ids and anti-Ids. In general, the findings confirm predictions based on the interpretation of recent kinetic studies.
Gronski
P
P
Research Laboratories of Behringwerke AG, Marburg/Lahn, W.-Germany.
Bauer
R
R
Bodenbender
L
L
Boland
P
P
Diderrich
G
G
Harthus
H P
HP
Kanzy
E J
EJ
Kühn
K
K
Schmidt
K H
KH
Walter
G
G
D000818:Animals; D000911:Antibodies, Monoclonal / Q000302:isolation & purification*; D006801:Humans; D007074:Immunoglobulin G / Q000302:isolation & purification*; D007130:Immunoglobulin Idiotypes / Q000302:isolation & purification*; D051379:Mice; D008854:Microscopy, Electron; D008968:Molecular Conformation
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D007130:Immunoglobulin Idiotypes; C044411:polymeric IgG