The expression of angiotensin-I converting enzyme (ACE; EC 220.127.116.11) in human circulating mononuclear cells was studied. T-lymphocytes contained the highest level of enzyme, approx. 28 times more per cell than monocytes. No activity was detected in B-lymphocytes. ACE was present mainly in the microsomal fraction, where it was found to be the major membrane-bound bradykinin-inactivating enzyme. An mRNA for ACE was detected and characterized after reverse transcription and amplification by PCR in T-lymphocytes and several T-cell leukaemia cell lines. We have previously observed that the interindividual variability in the levels of ACE in plasma is, in part, genetically determined and influenced by an insertion/deletion polymorphism of the ACE gene. To investigate the mechanisms involved in the regulation of ACE biosynthesis, the ACE levels of T-lymphocytes from 35 healthy subjects having different ACE genotypes were studied. These levels varied widely between individuals but were highly reproducible and influenced by the polymorphism of the ACE gene. T-lymphocyte levels of ACE were significantly higher in subjects who were homozygote for the deletion than in the other subjects. These results show that ACE is expressed in T-lymphocytes and indicate that the level of ACE expression in cells synthesizing the enzyme is genetically determined.
Angiotensin I-converting enzyme in human circulating mononuclear cells: genetic polymorphism of expression in T-lymphocytes
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O Costerousse, J Allegrini, M Lopez, F Alhenc-Gelas; Angiotensin I-converting enzyme in human circulating mononuclear cells: genetic polymorphism of expression in T-lymphocytes. Biochem J 15 February 1993; 290 (1): 33–40. doi: https://doi.org/10.1042/bj2900033
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