Table 1.
Potential roles of atypical memory B cells in the immune response to Plasmodium.
| Potential Role | Experimental Observations in Human Studies Supporting Potential Role | Antigen-specific | AtMBC a Definition | Reference |
|---|---|---|---|---|
| Immune Regulators | BCR crosslinking by FcRL5 and immune complexes may reduce BCR signalling | No | CD19+CD10−CD21−CD27−IgD−IgG+ | Sullivan et al., 2015 |
| T-bet+ atMBCs upregulated markers important for CD4+ T cell interactions | No | CD19+CD21−CD27−Tbethi | Obeng-Adjei et al., 2017 | |
| No | CD19+Tbet+ | Ambegaonkar et al., 2019 | ||
| Dysfunctional B Cells | Reduced antibody production in vitro | No | CD19+CD21−CD27− | Portugal et al., 2015 |
| No | CD19+CD10−CD21−CD27−IgD−IgG+ | Sullivan et al., 2015 | ||
| Downregulation of BCR signalling pathways compared with cMBCs | No | CD19+CD21−CD27−− | Portugal et al., 2015 | |
| No | CD19+CD21−CD27−Tbethi | Obeng-Adjei et al., 2017 | ||
| No | CD19+Tbet+ | Ambegaonkar et al., 2019 | ||
| Reduced proliferation | No | CD19+CD21−CD27− | Portugal et al., 2015 | |
| Reduced cytokine production | No | CD19+CD21−CD27− | Portugal et al., 2015 | |
| High frequency of extrafollicular cells in lymph node associated with low HIV-1 serum neutralisation | No | CD19hiT-bethi | Austin et al., 2019 | |
| Activated B Cells | CD11c+ B cell expansion and contraction observed in malaria patients | No | CD19+CD21−CD27− | Sundling et al., 2019 |
| Atypical markers induced in vitro by stimulation with IFNγ | No | CD19+Tbet+ | Ambegaonkar et al., 2019 | |
| No | IgD-CD27-CD11c+ CXCR5− | Zumaquero et al., 2019 | ||
| AtMBCs transiently arise in response to influenza vaccination | No | CD21loCD27−FcRL5+CD85jhiCD62Llo | Andrews et al., 2019 | |
| Pre-antibody Secreting Cells | pBLNK increased compared with unstimulated cells following BCR engagement | No | IgD−CD21−CD27−CXCR5−CD11c+IgA− | Jenks et al., 2018 |
| No | CD19+CD21−CD27−Tbethi | Obeng-Adjei et al., 2017 | ||
| No | CD19+Tbet+ | Ambegaonkar et al., 2019 | ||
| DN2 B cells differentiated into ASCs in the absence of BCR crosslinking | No | IgD−CD27−CD11c+CXCR5− | Zumaquero et al., 2019 | |
| Secretory Ig transcripts found in atMBCs but not in cMBCs | No | CD19+CD21−CD27−Ig+ | Muellenbeck et al., 2013 | |
| Autoreactive B Cells | Stimulated DN2 B cells differentiated into autoreactive plasma cells | No | IgD −CD21−CD27−CXCR5−CD11c+ | Jenks et al., 2018 |
| Antibodies from malaria-associated atMBCs have increased self- and polyreactivity | GMZ2 | CD19+CD21−CD27−Ig+ | Muellenbeck et al., 2013 | |
| atMBCs secrete autoantibodies upon in vitro stimulation | No | CD19+FcRL5+T-bet+ | Rivera-Correa et al., 2019 |
atMBCs, atypical memory B cells; BCR, B cell receptor; cMBCs, classical memory B cell; ASCs, antibody-secreting cells.