Figure 1.

CD52^hiCD4⁺ T cells inhibit CD52^loCD4⁺ T-cell activation through the release of cell surface CD52. GPI-anchored, membrane-bound CD52 core molecules from CD52^hiCD4⁺ T cells are released by phospholipase C cleavage. Free CD52 interacts with Siglec-10 on responder CD52^loCD4⁺ T cells and inhibits the activation of the responder cells by blocking Lck and Zap70 phosphorylation. GPI, glycosylphosphatidylinositol; Siglec, sialic acid-binding immunoglobulin-like lectin.