NEW MATERIAL:A monoclonal antibody (molecular weight: 20,000±2,000; isoelectric point pI=5.6±0.2; mobility: Rf=0.29±0.02 by Disc-PAGE; soluble in water, solution of salt, or buffer solution of phosphate, slightly soluble or insoluble in ethyl ether, etc.; color reaction: showing protein positive reaction by Lowry method, showing glucide positive reaction by phenol-sulfuric acid method, etc. showing cell disorder activity against KB cell and L929 cell; showing specificity to new lymphokine which is stable for ≥1mon by freezing preservation at -10°C).

USE: A diagnosticum for human diseases, etc.

PREPARATION: A warm-blooded animal except human is immunized against new lymphokine I as an antigen, an antibody-forming cell is collected from the animal, it is fused with a myeloma cell to give a fused cell, a fused cell capable of producing an anti-new lymphokine I antibody is selected from the prepared fused cell, it is multiplied, to give a monoclonal antibody showing specificity to new lymphokine I.