May have a pivotal role in cell differentiation of different cell types. May have a specific role in early thymocyte development. Signaling could be triggered by the binding of a lectin-like ligand to the CD24 carbohydrates, and transduced by the release of second messengers derived from the GPI-anchor. Modulates B-cell activation responses (By similarity). In association with SIGLEC10 may be involved in the selective suppression of the immune response to danger-associated molecular patterns (DAMPs) such as HMGB1, HSP70 and HSP90 (PubMed:19264983). Plays a role in the control of autoimmunity (PubMed:20200274). Interacts with SIGLEC10; the probable CD24:SIGLEC10 complex is proposed to inhibit HGMB1-mediated tissue damage immune response. In lymphoid, myeloid, and erythroid cells. The identity of the N- and O-linked polysaccharides are not reported in PubMed:1530634. The O-linked polysaccharides on Ser-30, Ser-41, Ser-43, and Thr-51 are probably the mucin type linked to GalNAc. Cd22/Siglec10 double-deficient mice develop autoimmune disease, which is not observed in single-deficient mice. Belongs to the CD24 family.