Characterization of a Monoclonal Antibody Directed Against the Phosphotyrosine Kinase p56lck, in Human T Cells

A monoclonal antibody (anti-p56lck) was generated against a fusion protein containing the residues 145–509 of the human p56lck, a lymphoeyte-specific membrane-associated protein tyrosine kinase. The involvement of this enzyme in T-cell transmembrane signalling seems to be an early and crucial event during T-cell receptor-mediated activation. We have produced a monoclonal antibody which recognizes p56lck in free form and when associated with CD4. H functions in western blot analysis and is capable of selectively blocking auto-phosphorylation of this kinase. This monoclonal antibody should be useful for investigating the role of p56lck in T-cell activation.