CD99 also known as MIC2 is a cell surface glycoprotein involved in leukocyte migration, T-cell adhesion, ganglioside GM1 and transmembrane protein transport, and T-cell death by a caspase-independent pathway.  CD99 plays a significant role in lymphocyte aggregation and adhesion. CD99 exists in two forms produced by alternative splicing: the major form promotes cellular adhesion, while the truncated form inhibits this process. This regulation of adhesion is vital, as CD99 modulates the interaction between lymphocytes and the intercellular adhesion molecule-1 (ICAM-1) through lymphocyte function-associated antigen-1 (LFA-1). Notably, overexpression of the truncated form of CD99 leads to a downregulation of LFA-1, which is associated with the Hodgkin′s and Reed-Sternberg (H-RS) phenotype in certain cells, underscoring the importance of CD99 in maintaining proper cell function and morphology.