Table 1: Characteristics of primary B cell subsets and their progenitors.

DifferentiationSubsetSurface phenotype

Progenitor subsets
(bone marrow)
Pro-BB220loCD43+
AA4.1+
Pre-BB220loCD43−, AA4.1+preBcR+
Immature (23−)B220lo, sIgM+, sIgD−, CD23−
Immature (23+)CD19+, B220+, sIgM+, sIgD−, CD23+
Transitional subsets (spleen)T1IgMhiCD23−, B220intAA4.1+
T2IgMhiCD23+, B220+AA4.1+
T3IgMloCD23+, B220+AA4.1+
Mature primary subsetsFollicular zoneIgMloCD23+, B220hiAA4.1−
Marginal zone CD19+IgMhiIgDlo CD23+ CD21+
B1CD43+ CD23− CD5+
T-independent responsesEarly antibody-forming cells/short-lived plasma cellsB220loCD19+slg+iclghi
T-dependent responsesEarly antibody-forming cells/short-lived plasma cellsB220loCD19+slg+iclghi
Germinal centerB220+CD19+GL7+
Long-lived plasma cellsB220loslg−iclg+
MemoryB220+slg+IgD−
Natural antibodiesPeritoneal B1a and B1bCD43+ CD23− CD5+