animals were immunized with the cloned cytotoxic T lymphocyte lines V4 and 243/2.5; spleen cells were fused with Sp2/0-Ag14 myeloma cells; L3T4 is expressed on mouse helper/induce T cells and is analogous to the human Leu-3/T4 molecule; the antibody profoundly blocks antigen specific murine class II MHC antigen reactive helper I lymphocyte lines; tested and found negative for ectromelia virus (mousepox)Tumorigenecity:Isoenzyme:IgG2bHistopathology:hybridoma; mouse(myeloma)Subculture:Split ratio:Media change:Reverse transcritase:Productionimmunoglobulin; monoclonal antibody; against mouse helper, inducer T cells (L3T4 antigen, CD4)