Abstract
Protein kinase C (PKC) activation and/or modulation of its isoenzyme expression play key roles in regulating the response of haematopoietic cells to both growth factors and non-physiological inducers of cell growth and differentiation. The level of PKC activities for both cytosol and particulate fractions of ALL and CLL cells are lower than those of AML type. Atypical AML blasts expressing T-cell associated CD2 and CD7 determinants have significantly lower PKC activities compared to typical AML blasts. Analyses of PKC isoforms (-α, -β, and -γ) show considerable variation with respect to leukaemic cell distributions and subcellular localisations. PKC-α and -β are usually the major species in cytosolic fractions, whereas PKC-γ is the predominant type in particulate fractions. All lymphoid cells express PKC-γ in the cytosol, albeit as a minor component, while the occurrence of cytosol PKC-γ in AML cells appears to be associated in particular with a typical lymphoid antigen expression.