The role of current and new discriminating markers in the immunodiagnosis of Hodgkin's disease and other phenotypically related lymphomas.

Recent data have shown that CD40 antigen and its ligand (CD40L), and the CD26 molecule are differentially expressed among Hodgkin's disease (HD) (CD40+, CD26, CD40L), peripheral T-cell (PTCL) (CD40L+/-, CD40, CD26) and CD30 positive anaplastic large cell (ALC) (CD26+, CD40L) lymphomas. Since CD40 molecule is consistently detected on Reed-Sternberg (RS) cells and their morphologic variants with a distinctive staining pattern. CD40 expression provides a new potential tool for the identification of RS cells of HD in fixed and paraffin-embedded material. Furthermore, the combined application of anti-CD40 and anti-CD26 MoAbs may discriminate HD from morphologically and immunophenotypically related ALC lymphomas. In fact a CD26+/CD40 profile is restricted to CD30 positive ALC lymphomas. Finally, the combined application of anti-CD40 and anti-CD40L MoAbs provides additional significant features in differentiating HD from PTCL due to the constant expression of CD40+/CD40L phenotype in HD and its absence in PTCL, which in turn express CD40/CD40L+/- phenotype.