Early research reported the discovery of lymphocytes as the instruments of adaptive or specific immunity. This branch of our immune system has the properties of recognizing a broad range of antigens and can undergo what is termed as clonal differentiation. While most B cells secrete antibodies specific to antigens, there are also memory B-cells. While their initial functions were listed as the vital players of the humoral (Ab-based) immunity, later studies showed that B lymphocytes can also produce cytokines that influence the functions of dendritic cells and T cells and also capture antigens for presentation. The cytokines released by B cells can control rejection of transplanted tissues, wound healing, T cell differentiation and organization of the lymphoid tissues.
Other interesting findings from research include the presence of non-self infectious danger sensors or receptors (Rcs) in large amounts and specific Toll like receptors (TLRs- Pathogen Recognition Receptors (PRRs)) on B cells. The cells also express Complement Receptor 2 (CR2/CD21) that functions in B-cell signalling and also a receptor for EBV, a herpes virus causing infectious mononucleosis. These multiple roles earned the cells the title: “B-cells are not only actors but also key regulators in the immune response” (Garraud et al, 2012).
B cells offer exciting platforms for research projects: for example, an article published in 2018 in Frontiers in Immunology explored the kinetics of B cell development. Given that the precisely coordinated process of B cell lymphopoiesis starts with pro-B cells undergoing various stages of maturation expressing Igα and Igβ. Studies have shown that the lack of expression of these proteins arrests the development of B cells and the stem cells remain at the pro-B cell stage. The differentiation of the B cells begins in the bone marrow and ends in the spleen. The team explored the factors involved in the expression of transitional 1 (T1) and transitional 2 (T2) B cells in the spleen. Given the importance of the B-cell receptor (BCR) signalling, such studies become important to study diseases such as B-cell lymphomas (chronic lymphocytic leukaemia).
Other aspects of disease also warrant detailed studies using B lymphocytes: the involvement of B cells in autoimmune diseases and immunodeficiencies have shown the presence of the BCR mutations. For example, hyper-IgM syndrome and common variable immune deficiency (CVID).
A combination of cutting edge technology and advancements can guide further research in B lymphocytes to offer glimpses to the intricate details of our immune system.
Garraud, O., Borhis, G., Badr, G., Degrelle, S., Pozzetto, B., Cognasse, F., & Richard, Y. (2012). Revisiting the B-cell compartment in mouse and humans: more than one B-cell subset exists in the marginal zone and beyond. BMC immunology, 13, 63. https://doi.org/10.1186/1471-2172-13-63.
Hobeika E, Dautzenberg M, Levit-Zerdoun E, Pelanda R and Reth M (2018) Conditional Selection of B Cells in Mice With an Inducible B Cell Development. Frontiers in Immunology. 9:1806. doi: 10.3389/fimmu.2018.01806
Tucker W. LeBien, Thomas F. Tedder; B lymphocytes: how they develop and function. Blood 2008; 112 (5): 1570–1580. doi: https://doi.org/10.1182/blood-2008-02-078071