Glycosylated recombinant human XCL1/lymphotactin exhibits enhanced biologic activity

Chemokines are a family of small, secreted chemoattractant cytokines that regulate distribution and function of leukocytes during immune responses. While most chemokines are members of the CC or CXC subgroups, XCL1, also known as lymphotactin, is the sole member of the C subgroup. XCL1 is produced by activated CD8+ T cells, NK cells, γδ T cells, and mast cells. XCL1 differs from other chemokines in that it contains only a single disulfide bond and a mucin-like domain at its carboxy terminus that is glycosylated. Understanding the biologic functions of chemokines has largely depended upon expression of these recombinant molecules in E. coli. To examine the effects of glycosylation on the biologic activity of XCL1, we designed constructs for expression of human XCL1 in insect S2 cells. Comparison of this material with that expressed in E. coli reveals that glycosylation significantly increases the biologic activity of XCL1.