Enhanced binding of low-affinity antibodies interacting simultaneously with targeted cell surface molecules and Fc receptor.
The possibility that different forms of class I molecules might be expressed on the cell surface of lymphocytes has been investigated periodically over the past several decades. A series of major histocompatibility complex (MHC) class I-specific monoclonal antibodies, including the commonly used antibodies 64-3-7 and 25-D1.16, bind B cells differentially, suggesting the existence of differentially expressed class I-associated cell surface determinants on B lymphocytes. However, the ability of antibodies to bind cells is determined by the sum of interactions between the antibodies and the molecules expressed on the cell surface. The interactions of class I-specific antibodies with B cells were dissected, revealing dual specificity of the antibodies for the targeted class I molecules, as well as to Fc receptors preferentially expressed by B cells. We demonstrate that antibodies simultaneously bind targeted class I molecules and Fc receptors expressed on the surface of B cells. Simultaneous binding to two cell surface structures significantly enhances the class I-specific binding pattern of certain antibodies by increasing their avidity, leading to apparent cell-specific differences in MHC expression patterns. We conclude that no differences in MHC structures need be postulated to account for the observed binding patterns.
Mendez-Fernandez
Y V
YV
Department of Immunology, Mayo Clinic and Graduate Schools, Mayo Clinic, Rochester, MN 55905, USA.
Pogulis
R P
RP
Block
M S
MS
Johnson
A J
AJ
Kuhns
S T
ST
Allen
K S
KS
Hansen
M J
MJ
Pease
L R
LR
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D015703:Antigens, CD / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D004527:Egg Proteins / Q000276:immunology; D000939:Epitopes; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments; D017452:Receptors, IgG / Q000276:immunology*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D004527:Egg Proteins; D000939:Epitopes; D018985:Epitopes, B-Lymphocyte; C080571:Fc gamma receptor IIB; D015395:Histocompatibility Antigens Class I; C110366:OVA-8; D010446:Peptide Fragments; D017452:Receptors, IgG; D010047:Ovalbumin