PROTEIN-TYROSINE KINASES AND TNF-ALPHA SECRETION IN HUMAN MONOCYTES

The role of protein tyrosine kinases (PTK) in TNF alpha secretion by h uman monocytes was investigated in this report. We showed that an immu nomodulator such as Nocardia lysozyme digest (NLD) and a particulate a gonist, zymosan, stimulated an increase in tyrosine phosphorylation of several endogenous substrates including 53-56 kDa protein which was t he predominant phosphoprotein. In addition, NLD and zymosan induced TN F alpha secretion which was impaired by a PTK inhibitor, tyrphostin. W e suggest that a cascade of kinases including PTK is involved in NLD a nd zymosan signalling.