Interactions between murine B lymphocyte surface membrane molecules. Loaded but not free receptors for complement and the Fc portion of IgG co-cap independently with cross-linked surface Ig.
We have investigated the possible physical interactions between CR, receptors for the Fc gamma R and surface Ig (sIg) on the surface membrane of murine B lymphocytes. We used the rat mAb to murine CR, 8C12, and 7G6, as CR ligands, and soluble Ag-antibody complexes as FcR ligands; and F(ab')2 fragments of rabbit antibodies specific for mouse IgM and IgD as sIg ligands. We have found that: 1) sIg, CR, and Fc gamma R are not directly linked, because capping of any one did not affect the expression of the others; 2) the mAb 8C12 and 7G6 failed by themselves to cross-link CR; 3) soluble Ag-antibody complexes crosslinked some, Fc gamma R on a minority of Fc gamma R+ lymphocytes; 4) once loaded with anti-CR mAb, CR co-capped with sIg when sIg was cross-linked; 5) once loaded with Ag-antibody complexes, Fc gamma R also co-capped with sIg when sIg was sIg was cross-linked; 6) loading of Fc gamma R did not affect the co-capping of surface CR with cross-linked sIg and conversely, loading of CR did not affect the co-capping of Fc gamma R with cross-linked sIg; only loaded CR or Fc gamma R co-capped with sIg regardless of the status of the other surface molecule; 7) neither loaded nor free CR co-capped with cross-linked Fc gamma R, and neither loaded nor free Fc gamma R co-capped with cross-linked CR. These results demonstrate that both Fc gamma R and CR independently become associated with sIg when either receptor is loaded and sIg is cross-linked.
Tsokos
G C
GC
Department of Medicine, National Institute of Diabetes, Digestive, and Kidney Diseases, Bethesda, MD.
Kinoshita
T
T
Thyphronitis
G
G
Patel
A D
AD
Dickler
H B
HB
Finkelman
F D
FD
D000818:Animals; D000936:Antigen-Antibody Complex / Q000378:metabolism; D000943:Antigens, Differentiation / Q000378:metabolism*; D001402:B-Lymphocytes / Q000502:physiology* / Q000648:ultrastructure; D003165:Complement System Proteins / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D007152:Immunologic Capping; D066298:In Vitro Techniques; D008024:Ligands; D051379:Mice; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D011951:Receptors, Complement / Q000378:metabolism*; D011961:Receptors, Fc / Q000378:metabolism*; D017452:Receptors, IgG
D000936:Antigen-Antibody Complex; D000943:Antigens, Differentiation; D007074:Immunoglobulin G; D008024:Ligands; D011947:Receptors, Antigen, B-Cell; D011951:Receptors, Complement; D011961:Receptors, Fc; D017452:Receptors, IgG; D003165:Complement System Proteins