C-X-C chemokine receptor type 5 (CXC-R5) also known as CD185 (cluster of differentiation 185) or Burkitt lymphoma receptor 1 (BLR1) is a G protein-coupled seven transmembrane receptor for chemokine CXCL13 (also known as BLC) and belongs to the CXC chemokine receptor family. It enables T cells to migrate to lymph node B cell zones. In humans, the CXC-R5 protein is encoded by the CXCR5gene.
The BLR1 / CXCR5gene is specifically expressed in Burkitt's lymphoma and lymphatic tissues, such as follicles in lymph nodes as well as in spleen. The gene plays an essential role in B cell migration. Recently, it was shown that CXCR5 overexpression in breast cancer patients highly correlates with lymph node metastases, and elevated CXCR5 expression may contribute to abnormal cell survival and migration in breast tumors that lack functional p53 protein. Minor allele of SNP rs630923, located in the area of CXCR5 gene promoter and associated with the risk of multiple sclerosis, is responsible for appearance of MEF2C-binding site resulted in reduced CXCR5 gene promoter activity in B-cells during activation, that could lead to decreased autoimmune response 
CXCR5 has been shown to be expressed on both CD4 and CD8 T cells, though it is often regarded as the defining marker for T Follicular Helper (Tfh) cells.
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