B Lymphocytes: Development, Tolerance, and Their Role in Autoimmunity—Focus on Systemic Lupus Erythematosus

Table 1

Characteristics of primary B cell subsets and their progenitors.

Differentiation	Subset	Surface phenotype
Progenitor subsets; (bone marrow)	Pro-B	B220loCD43+
		AA4.1+
	Pre-B	B220loCD43−, AA4.1+preBcR+
	Immature (23−)	B220lo, sIgM+, sIgD−, CD23−
	Immature (23+)	CD19+, B220+, sIgM+, sIgD−, CD23+
Transitional subsets (spleen)	T1	IgMhiCD23−, B220intAA4.1+
	T2	IgMhiCD23+, B220+AA4.1+
	T3	IgMloCD23+, B220+AA4.1+
Mature primary subsets	Follicular zone	IgMloCD23+, B220hiAA4.1−
	Marginal zone	CD19+IgMhiIgDlo CD23+ CD21+
	B1	CD43+ CD23− CD5+
T-independent responses	Early antibody-forming cells/short-lived plasma cells	B220loCD19+slg+iclghi
T-dependent responses	Early antibody-forming cells/short-lived plasma cells	B220loCD19+slg+iclghi
	Germinal center	B220+CD19+GL7+
	Long-lived plasma cells	B220loslg−iclg+
	Memory	B220+slg+IgD−
Natural antibodies	Peritoneal B1a and B1b	CD43+ CD23− CD5+