Characterization ofa bovineleucocyte differentiation antigen of145,000 MW restricted toB lymphocytes

SUMMARY A new bovine B-cell differentiation antigen isdescribed thatisdetected bythreemonoclonal antibodies (mAb). Theantigen isnotanimmunoglobulin andisprecipitated fromperipheral Bcells asamolecule withan approximate molecular weight (MW)of120,000 or145,000 before andafter reduction, respectively. Dataobtained fromtwo-colour cytofluorimetry andimmunohistochemistry confirmed that theantigen was foundonly on matureBcells andoncells withdendritic morphology inthefollicles oftheorganized lymphoid tissues. Itslevel ofexpression isdirectly correlated withthat ofIgMon peripheral bloodBcells andTheileria parva-transformed B cells. Themarkerwas also expressed on theperipheral cells whichexpressed surface IgG.Basedon theantigen's cellular distribution, biochemistry andhistochemistry, itisconsidered tobeanalogous tothehumanCD21 antigen.