The changes in cytosolic aminopeptidase (c-AP: EC 3. 4. 11. 1) activity in mitogenstimulated lymphocytes were investigated. Phytohaemagglutinin (PHA) as the T lymphocyte mitogen and
Staphylococcus aureus cowan I (SAC) as the B lymphocyte mitogen were used to differentiate the association between c-AP activity and T/B lymphocyte stimulation. Significant increases of c-AP specific activity and [
3H]-thymidine incorporation were observed in PHA-stimulated whole lymphocytes, and more increases were observed in the fractionated T cell enriched population. On the contrary, c-AP activities in SAC-stimulated whole lymphocytes and B cell enriched population were not increased, despite a significant increase in[
3H]-thymidine incorporation. These results indicate that increases of c-AP activity may be closely associated with T lymphocyte activation, but not with that of B lymphocytes.
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