A majority of suppliers have reported the clone SPM545 to be a mouse monoclonal antibody specific to the human gene, C4A, or Complement C4A (Rodgers blood group). Other suppliers describe clone SPM545 to be a mouse monoclonal antibody against human C4B, or complement C4B (Chido blood group). Indicated applications for antibody clone SPM545 include immunohistochemistry, immunofluorescence, and ELISA.