Differential control of CD22 ligand expression on B and T lymphocytes, and enhanced expression in murine systemic lupus.
OBJECTIVE
CD22, a B cell-restricted transmembrane glycoprotein, regulates B cell antigen receptor signaling upon interaction with alpha2,6-linked sialic acid-bearing glycans, which act as ligands and are expressed on B and T cells. In this study, we investigated how the expression of CD22 ligand (CD22L) is modulated following lymphocyte activation or during the course of systemic lupus erythematosus (SLE).


METHODS
The expression levels of CD22L on B and T cells in nonautoimmune mice were assessed by flow cytometric analysis using a soluble recombinant form of CD22, following stimulation with antigen or mitogen in vitro. In addition, the expression levels of CD22L on circulating lymphocytes were correlated with the progression of SLE in lupus-prone mice.


RESULTS
We observed a constitutive expression of CD22L on mature B cells, but not T cells, in nonautoimmune mice. However, CD22L levels were up-regulated selectively on T cells (but not B cells) stimulated with antigens in vitro, while their expression levels on B cells was up-modulated following polyclonal activation with lipopolysaccharide. Furthermore, expression of CD22L was increased on circulating B cells (and to a lesser extent on T cells) in parallel with progression of SLE in several different lupus-prone mice and in a cohort of (C57BL/6 x [NZB x C57BL/6.Yaa]F(1)) backcross mice.


CONCLUSIONS
The expression of CD22L is differentially regulated in B and T cells, and high expression of CD22L on circulating B cells is a marker for development of severe SLE, suggesting a role for CD22-CD22L interactions in SLE as well as in the regulation of humoral immunity.
Lajaunias
Frédéric
F
Department of Pathology, University of Geneva, Geneva, Switzerland.
Ida
Akinori
A
Kikuchi
Shuichi
S
Fossati-Jimack
Liliane
L
Martinez-Soria
Eduardo
E
Moll
Thomas
T
Law
Che-Leung
CL
Izui
Shozo
S
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D001402:B-Lymphocytes / Q000378:metabolism*; D015815:Cell Adhesion Molecules; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D037102:Lectins / Q000378:metabolism*; D008024:Ligands; D008180:Lupus Erythematosus, Systemic / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D008181:Lupus Nephritis / Q000378:metabolism / Q000401:mortality / Q000473:pathology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D011994:Recombinant Proteins; D051918:Sialic Acid Binding Ig-like Lectin 2; D013154:Spleen / Q000166:cytology / Q000276:immunology; D015996:Survival Rate; D013601:T-Lymphocytes / Q000378:metabolism*; D015854:Up-Regulation
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C497868:Cd22 protein, mouse; D015815:Cell Adhesion Molecules; D037102:Lectins; D008024:Ligands; D011947:Receptors, Antigen, B-Cell; D011994:Recombinant Proteins; D051918:Sialic Acid Binding Ig-like Lectin 2