Truncated B-lymphocyte antigen CD19 (CD19t) (CD19t)

Truncated CD19 (CD19t) is a modified, non-signaling variant of the human B-lymphocyte antigen CD19, engineered for use as a selection and tracking marker in adoptive cell therapies like CAR-T (Wang et al., 2011). It consists of the extracellular and transmembrane domains of the CD19 protein but lacks the highly conserved cytoplasmic signaling domain, which prevents it from activating endogenous B-cell signaling pathways such as the PI3K/Akt pathway (UniProt P15391). In clinical manufacturing, CD19t is often co-expressed with a chimeric antigen receptor (CAR) using a 2A ribosomal skip sequence, allowing for the identification and enrichment of successfully transduced T cells via anti-CD19 immunomagnetic beads (Paszkiewicz et al., 2016). Beyond selection, CD19t serves as a safety switch or suicide gene target; if a patient experiences severe toxicity, such as cytokine release syndrome, the administration of an anti-CD19 antibody can trigger the depletion of the engineered T cells through antibody-dependent cellular cytotoxicity (ADCC). It also facilitates the long-term monitoring of CAR-T cell persistence in a patient's peripheral blood using standard flow cytometry techniques. While highly effective as a tool, its use requires consideration of potential immunogenicity and the risk of unintended depletion if the patient receives other CD19-targeted therapies.

Other names

tCD19CD19tTruncated CD19CD19 delta-cytoplasmicCD19ΔcytoCD19 selection marker

Provides a non-signaling extracellular epitope for the enrichment of transduced cells and serves as a target for antibody-dependent cellular cytotoxicity (ADCC) to eliminate engineered cells if necessary.