Xcl1

XCL1, also called "chemokines (C motif) ligand 1" or lymphotactin, is a small cytokine that belongs to the XC chemokine family. The coding gene is located on chromosome 1 q24.2. XCL1 induces reactive, inflammatory processes on infectious agents (e.g. on E. coli, Stapyhylococcus aureus, various viruses), activating and chemotactic functions on T-cells and dendritic cells. The chemokine develops its functions by binding to the chemokine receptor XCR1.

XCL1 is found in high concentrations in the spleen, thymus, gastrointestinal tract and peripheral leukocytes. In lower concentrations, the chemokine can also be detected in the lung, prostate and ovary.

The chemokine is formed by activated T cells (CD8+ T cells, NK cells). In humans, the activities of XCL1 are closely coordinated with the chemokine XCL2, whose coding gene is located on the same gene locus.

In viruses, XCL1 acts directly with the external viral envelope glycoprotein gp120, thus blocking the progression of HIV-1 infection.

Some data indicate that XCL1 is expressed in CD4+ and CD8+ T cells in granulomatosis with polyangiitis (Wegner's granulomatosis). The results suggest that this cytokine plays an essential role in the pathogenesis of this disease.

In bronchial asthma, an association between dysregulated XCL1 expression and a reduced activity of Treg was found.

1. Huang H et al(2001) Neutrophils and B cells express XCR1 receptor and chemotactically respond to lymphotactin. Biochem Biophys Res Commun 281:378-382.
2. Lei Y et al (2012) XCL1 and XCR1 in the immune system. Microbes Infect 14:262-267.
3. Nguyen KD et al (2008) XCL1 enhances regulatory activities of CD4+ CD25(high) CD127(low/-) T cells in human allergic asthma. J Immunol 181:5386-5395.
4. Ohta T et al (2016) Crucial roles of XCR1-expressing dendritic cells and the XCR1-XCL1 chemokine axis in intestinal immune homeostasis. Sci Rep 6:23505.
5. Yamazaki C et al (2010) Conservation of a chemokine system, XCR1 and its ligand, XCL1, between human and mice. Biochem Biophys Res Commun 397:756-761.