Table 1.
Common proteins that are used to differentiate B cell subsets.
| Marker | Function | Reference |
|---|---|---|
| CD1d | May enable B cells to present antigens to invariant NKT cells Expressed in naïve and memory B cells, in plasma cells and in regulatory B cells |
(24) |
| CD5 | Negative regulator of BCR signalling Protects B cells from apoptosis after BCR stimulation Supports B cell survival via IL-10 production |
(25) |
| CD10 | Role in pre-B cell maturation and differentiation | (26) |
| CD11b | Forms part of the complement receptor 3 present on the surface of B cells | (27) |
| CD11c | Integrin, alpha X (complement component 3 receptor 4 subunit) (ITGAX) found on activated B cells | (27) |
| Expressed on age-associated B cells | (28) | |
| Marks memory cells, precursors of antibody-secreting cells | (29) | |
| CD19 | Co-receptor required for BCR signal transduction | (30) |
| Cooperates with CD21 for BCR-independent signalling | (31) | |
| CD20 | Pan-B cell surface marker for mature B cells Lost during terminal B cell differentiation |
(32) |
| Regulator of calcium flux triggered by BCR Required for optimal B cell responses to T-independent antigens |
(33) | |
| CD21 | B cell co-receptor required to enhance BCR signalling, complement receptor | (34) |
| CD24 | On activated B cells, CD24 facilitates CD4+ T cell clonal expansion via co-stimulation | (35) |
| Role in the regulation of B cell development | (36) | |
| CD27 | Promotes the differentiation of memory B cells into plasma cells | (37) |
| Marker of B cell activation/memory | (38) | |
| CD38 | Involved in B cell differentiation | (39) |
| Crosslinking of CD38 to the BCR reduces the threshold for B cell activation | (40) | |
| CD44 | May play a role in antigen-dependent B cell differentiation | (41) |
| Interacts with the polysaccharide hyaluronan (HA) in the extracellular matrix | (42) | |
| CD45 | Central regulator of BCR signalling | (43) |
| CD77 | GC B cell entering apoptosis (CD77+) | (44) |
| Marker of GC B lymphocytes | (45) | |
| Discriminator of centroblasts (CD77+) and centrocytes (CD77-) | (46) | |
| CD80/CD86 | Co-stimulatory molecules | (47, 48) |
| CD138 | Syndecan 1, regulates the survival of plasma cells and long-term humoral immunity | (49) |
| FcRL4 | Expressed on the surface of a subset of memory B cells | (50, 51) |
| Expressed on the surface of atypical memory B cells | (52) | |
| Potential function in mucosal immunity | (53) | |
| FcRL5 | Expressed on the surface of atypical memory B cells | (52) |
| Novel IgG receptor, inhibits BCR signalling May have a dual signalling capacity (CD21 co-engagement may result in B cell activation) |
(54) | |
| T-bet | Promotes the survival of memory B cells and IgG2a isotype switching | (55, 56) |
Brief descriptions of the putative protein functions are given with associated references, but often the precise role of the proteins within B cell subpopulations may not be clear.