Monoclonal antibody OPD4 is reactive with CD45RO, but differs from UCHL1 by the absence of monocyte reactivity.

Monoclonal antibody OPD4 was described as a novel monoclonal antibody recognizing a helper/inducer T-cell subset in paraffin-tissue sections. The authors have analyzed this reagent with respect to its molecular weight, reactivity with leukocyte common antigen (LCA) transfectants and cell and tissue distribution. OPD4 was found to be reactive with the 180 kd molecular weight isoform of the leukocyte common antigen family, similar to antibody UCHL1 and therefore can be considered as a CD45RO reagent. The only difference in distribution was found to be the absence of OPD4 reactivity with peripheral blood monocytes. Since OPD4 recognizes the same antigen on T cells as UCHL1, both reagents do not need applied in the immunophenotyping of lymphomas.