the possibility that th-induced b cell proliferation may be restricted at the effector ( th-b cell ) level was addressed by fractionating b cell populations into `` '' activated '' '' and `` '' resting '' '' subsets by discontinuous percoll density gradient centrifugation and further purification by employing a monoclonal antibody directed against an antigen expressed on activated b cells ( 4f2 ) .
C1155008
b cell
C0004561
b cell