Quantification of aminopeptidase N mRNA in T cells by competitive PCR.
The aminopeptidase N (CD13, EC 3.4.11.2) is a well-characterized surface molecule expressed in a variety of cell types and species. Recent data indicate an expression of the APN mRNA and the corresponding aminopeptidase activity in human peripheral T cells and related cell lines as well. Here, the sensitive method of competitive PCR was used to quantify low amounts of APN mRNA in T cell lines. An APN cDNA fragment enshortened by a deletion of 87 bp was used as an internal APN-specific standard. The myelo-monocytic cell line U937 and the lymphoid T cell lines HuT78 and H9 contain 2.3 x 10(7), 5.9 x 10(6) and 5.6 x 10(6) copies/micrograms total RNA, corresponding to 160, 70 and 50 copies/cell, respectively. These data have been confirmed by determination of the APN activity, that represents a fraction only of the total cellular neutral aminopeptidase activity in hematopoetic cells. In the case of the CD13-positive cell line U937, approximately 60-70% of the total neutral aminopeptidase activity could be attributed to APN. In contrast, only a minor fraction (5-20%) of the cellular neutral aminopeptidase activity in the T cell lines H9 and HuT78 represents APN. The results suggest that APN gene expression within the hematopoetic system is not restricted to myelo-monocytic cells, instead a low APN expression may be a common feature of lymphocytes, at least of T cells, too.
Wex
T
T
Department of Internal Medicine, University of Magdeburg, Germany.
Lendeckel
U
U
Wex
H
H
Frank
K
K
Ansorge
S
S
D001483:Base Sequence; D001667:Binding, Competitive; D018826:CD13 Antigens / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis*; D015183:Restriction Mapping; D013601:T-Lymphocytes / Q000737:chemistry*
D012333:RNA, Messenger; D018826:CD13 Antigens