The 104 monoclonal antibody specifically reacts with the mouse CD45 molecule, the Leukocyte Common Antigen (LCA) which occurs in the alloantigen CD45.2-expressing mouse strains (C57BL/6, CBA, 129, A, AKR, C58, DBA/1, DBA/2, BALB/c, and C3H/He). The 104 monoclonal antibody does not react with the leukocytes of the CD45.1-expressing mouse strains (DA, SJL/J, RIII, and STS/A).

The CD45 molecule is a member of the Protein Tyrosine Phosphatase (PTP) family, because its intracellular region contains two PTP domains. The extracellular region’s variability is caused by different levels of glycosylation, and the splicing of the 4, 5, and 6 exons.

The isoforms found in the mouse strains depend on the activation state, maturation stage and cell type, and are very important in B and T lymphocytes antigen receptor signal transduction. The 104 antibody inhibits some of the B lymphocytes responses, reduces the serum IgG levels, and influences the autoimmune renal pathology.