The leukocyte surface molecule CD99 is an integral membrane glycoprotein encoded 
by the E2/MIC2 gene. This molecule is broadly expressed on cells of the 
hematopoietic system and displays two surface forms, a long 32 kDa form and a 
short 28 kDa form. While the complete function of the CD99 molecule is unclear, 
it has been reported to be involved in regulation of cell adhesion, migration, 
and apoptosis. Thus, several CD99 monoclonal antibodies (MAbs) have been 
generated for biochemical and functional studies of the CD99 molecule. In the 
present study two CD99 MAbs, MT99/1 and MT99/2, were produced. The MAbs 
recognized different epitopes of the CD99 molecule. MAb MT99/1, but not MT99/2, 
was appropriate for biochemical characterization. Binding of MAb MT99/1 with its 
epitope led to the induction of cell adhesion and apoptosis. The generated MAbs 
can be used for future study of the function and mechanism of the CD99 molecule, 
including its role in the immune system, and may have application in tumor 
diagnosis and treatment.