A unique CD72 epitope suggests a potential interaction with Fc gamma RII/CD32 on B lineage lymphocytes.
It has long been known that ligation of the transmembrane CD72 glycoprotein delivers signals to B lymphocytes, with the outcome depending on context. Of particular interest is its ability to function as a counter-receptor/ ligand for the CD100 semaphorin protein. We have now obtained evidence that CD72 physically interacts on the lymphocyte membrane with Fcgamma receptor II (CD32). The association was first revealed with a new monoclonal antibody that recognizes polymorphic determinants on murine CD72. Although the specificity for CD72 was clear from immunoblotting, transfection and other experiments, staining with this reagent was inhibited when cells were pretreated with an Fc receptor-blocking antibody (CD16/CD32 specific). Furthermore, confocal microscopy revealed that the two molecules co-distributed on viable B cells. We also used the antibody to determine when CD72 becomes available to maturing lymphocytes. The marker is first acquired as large pre-B cells and enter the IL-7 independent phase of maturation within bone marrow. Subsequent interactions between CD72 and CD32 may cooperatively deliver negative signals that modulate humoral immune responses.
Yamashita
Yoshio
Y
Immunobiology & Cancer Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
Phee
Hyewon
H
Tudor
Kim-Sue R S
KS
Rossi
Maria Isabel D
MI
Parnes
Jane R
JR
Coggeshall
K Mark
KM
Kincade
Paul W
PW
D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D019556:COS Cells; D045744:Cell Line, Tumor; D019070:Cell Lineage / Q000276:immunology*; D002522:Chlorocebus aethiops; D018985:Epitopes, B-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051381:Rats; D017208:Rats, Wistar; D017452:Receptors, IgG / Q000378:metabolism*
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C513972:CD72 antigen, mouse; D018985:Epitopes, B-Lymphocyte; D008562:Membrane Glycoproteins; D017452:Receptors, IgG