Selective expansion of a monocyte subset expressing the CD11c dendritic cell marker in the Yaa model of systemic lupus erythematosus.
OBJECTIVE
Monocytosis is a unique cellular abnormality associated with the Yaa (Y-linked autoimmune acceleration) mutation. The present study was designed to define the cellular mechanism responsible for the development of monocytosis and to characterize the effect of the Yaa mutation on the development of monocyte subsets.


METHODS
We produced bone marrow chimeras reconstituted with a mixture of Yaa and non-Yaa bone marrow cells bearing distinct Ly-17 alloantigens, and determined whether monocytes of Yaa origin became dominant. Moreover, we defined the 2 major inflammatory (Gr-1+,CD62 ligand [CD62L]+) and resident (Gr-1-,CD62L-) subsets of blood monocytes in aged BXSB Yaa male mice, as compared with BXSB male mice lacking the Yaa mutation.


RESULTS
Analysis of the Ly17 allotype of blood monocytes in chimeric mice revealed that monocytes of both Yaa and non-Yaa origin were similarly involved in monocytosis. Significantly, the development of monocytosis paralleled a selective expansion of the resident monocyte subset compared with the inflammatory subset, and the former expressed CD11c, a marker of dendritic cells. Neither monocytosis nor the change in monocyte subpopulations, including CD11c expression, was observed in Yaa-bearing C57BL/6 mice, in which systemic lupus erythematosus (SLE) fails to develop.


CONCLUSIONS
Our results suggest that Yaa-associated monocytosis is not attributable to an intrinsic abnormality in the growth potential of monocyte lineage cells bearing the Yaa mutation and that the Yaa mutation could lead to the expansion of dendritic cells, thereby contributing to the accelerated development of SLE.
Amano
Hirofumi
H
University of Geneva, Geneva, Switzerland.
Amano
Eri
E
Santiago-Raber
Marie-Laure
ML
Moll
Thomas
T
Martinez-Soria
Eduardo
E
Fossati-Jimack
Liliane
L
Iwamoto
Masahiro
M
Rozzo
Stephen J
SJ
Kotzin
Brian L
BL
Izui
Shozo
S
D000818:Animals; D000974:Antibodies, Antinuclear / Q000032:analysis; D015551:Autoimmunity / Q000235:genetics*; D015415:Biomarkers; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D039521:CD11c Antigen / Q000378:metabolism*; D049109:Cell Proliferation; D002678:Chimera; D003713:Dendritic Cells / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D007964:Leukocytosis; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D008297:Male; D051379:Mice; D008814:Mice, Inbred NZB; D009000:Monocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D014998:Y Chromosome / Q000235:genetics* / Q000276:immunology
D000974:Antibodies, Antinuclear; D015415:Biomarkers; D039521:CD11c Antigen