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T Cells:Regulation and Cellular Immunity
Published in Constantin A. Bona, Francisco A. Bonilla, Textbook of Immunology, 2019
Constantin A. Bona, Francisco A. Bonilla
This molecule is found on all T cells, and a certain subset of B cells (see Chapter 5); it belongs to a family of proteins known as scavenger receptors. CD5 is a monomer with Mr 67 kDa and also plays a role in T cell activation. CD5 interacts with CD72 on B cells; it has a long intracytoplasmic portion which is a substrate for the tyrosine kinases lck and fyn. CD5 has a close association with the CD3 ζ chains, and phosphorylation of CD5 occurs within seconds of TCR binding. Stimulation via CD5 has been shown to mobilize intracellular calcium, increase cGMP and production of IL-2 and IL-2 receptors (IL-2R).
Monocyte and lymphocyte membrane markers: Ontogeny and clinical significance
Published in Gabriel Virella, Medical Immunology, 2019
Scott Sugden, Damien Montamat-Sicotte, Karen K. Yam, Joseph Murphy, Bader Yassine Diab, Virginia Litwin
CD72 is a type II transmembrane protein of the C-type lectin family. CD72 is expressed on B cells, dendritic cells, and a subpopulation of T cells and macrophages. CD72 contains intracellular ITIMs and is known to have an inhibitory role in B-cell signaling.
Blockage of CD72 reduces B cell proliferation in immune thrombocytopenic purpura, involving interleukin 1 and macrophage migration inhibitory factor secretion
Published in Hematology, 2022
Jianhui Xu, Jingwen Du, Yuxia Zhong, Honghao Zhang, Lijuan Zhou, Qianqian Yao
CD72 is a B cell transmembrane protein containing a C-type lectin-like domain in the extracellular region and an immunoreceptor tyrosine-based inhibition motif in the cytoplasmic region [13]. CD72 is commonly considered as a negative regulator for B cell receptor (BCR) signaling. However, it has been demonstrated to exert dual effects on B lymphocyte development and function. In mature B cells, CD72 acts a positive effect by transient recruitment of CD19 [14]. In immature B cells, CD72 negatively regulates BCR signaling by its simultaneous phosphorylation and recruitment of SHP-1 [15]. The interaction between CD72 and its ligand CD100 is required for proper B cell homeostasis [16] and propagated not only B cell initial activation but also B cell differentiation into plasma cells [17]. This interaction even promotes the secretion of interferon and tumor necrosis [18]. Thus, CD72 plays a critical role in B cell survival and function in vivo.
Inhibitory B cell co-receptors and autoimmune diseases
Published in Immunological Medicine, 2019
Inhibitory B cell co-receptors such as CD22 and CD72 have been shown to regulate expansion of B reg cells. CD22–/– mice show expansion of CD1dhi B cells and B cells that produce IL-10 upon stimulation with LPS, PMA, and ionomycin [65]. CD72–/– mice show expansion of LAG-3+ plasmablasts, and B cells that produce IL-10 upon Salmonella infection [14]. These findings clearly demonstrate that both CD22 and CD72 inhibit B reg expansion. TLR signaling has been shown to induce IL-10 production and expansion of B reg cells [65,66]. Because CD22 negatively regulates B cell activation induced by TLR ligands such as LPS, CpG and imiquimod [67], CD22 may inhibit expansion of B reg cells by negatively regulating B cell responses to TLR ligands. It is not yet known whether CD72 regulates B cell activation induced by TLR ligands. However, CD72 recognizes the endogenous TLR7 ligand Sm/RNP as a specific ligand, and inhibits B cell responses to Sm/RNP [13]. Suppression of responses to Sm/RNP might be involved in inhibition of B reg expansion by CD72.