CD5 Gene

The CD5 gene (CD5 molecule) is a protein-coding gene located on chromosome 11q12.2. The CD5 gene encodes a receptor protein of the same name, a member of the signal transducing cysteine-rich scavenger receptor (SRCR) class I superfamily. CD5 as well as the closely related CD6 are mainly detected on lymphocytes. Both receptors are involved in the modulation of cell activation and differentiation processes triggered by clonotypic antigen-specific receptors on T and B cells (TCR and BCR, respectively). To perform such a relevant immunomodulatory function, the extracellular region of CD5 and CD6 interacts with soluble and/or cell-bound endogenous counter-receptors, but also with microbial associated molecular patterns (MAMPs).

Genetically engineered mouse models indicate that the absence or blockade of CD5- and CD6-mediated signaling leads to defective immune responses that may be harmful or beneficial in certain pathological conditions such as infections, tumor diseases, or in autoimmunoglastic processes. There is an interest in using soluble CD5 and CD6 receptors as immunotherapeutics (Velasco-de Andrés M et al. 2020).

Diseases associated with CD5 include thymic carcinoma and Richter syndrome , also called Richter transformation. This is a transformation of B-cell chronic lymphocytic leukemia (CLL) or hairy cell leukemia into a fast-growing diffuse large B-cell lymphoma, a form of non-Hodgkin's lymphoma that is treatment-resistant and has a poor prognosis (Tsimberidou AM et al. 2007).

CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) is associated with poorer survival . CD5+ DLBCL has a high frequency of p53 overexpression, and CD5 enhances the negative effect of p53 overexpression in DLBCL (Zhao P et al. 2019).

Related pathways include hematopoietic stem cells and lineage-specific markers. An important paralog of this gene is DMBT1.

1. Sarrias MR et al (2004) The Scavenger Receptor Cysteine-Rich (SRCR) domain: an ancient and highly conserved protein module of the innate immune system. Crit Rev Immunol 24:1-37.
2. Tsimberidou AM et al (2007) Richter's transformation in chronic lymphocytic leukemia. Curr Hematol Malig Rep 2:265-271.
3. Velasco-de Andrés M et al (2020) Soluble CD5 and CD6: lymphocytic class I scavenger receptors as immunotherapeutic agents. Cells 9:2589.
4. Zhao P et al (2019) CD5 expression correlates with inferior survival and enhances the negative effect of p53 overexpression in diffuse large B-cell lymphoma. Hematol Oncol 37:360-367.