Cellular source(s) of platelet-activating-factor acetylhydrolase activity in plasma.
Platelet activating factor (PAF) is immediately degraded and inactivated in the bloodstream by plasma PAF acetylhydrolase (PAF-AH). Although plasma PAF-AH-like activity was secreted in vitro from various cell types such as macrophages and hepatocytes, the exact cellular source(s) of this enzyme activity in vivo remains unclear. There is a naturally-occurring missense mutation (V279F) in the plasma PAF-AH gene in the Japanese population which results in complete loss of the enzyme activity. We analyzed 52 Japanese who had received an allogeneic bone marrow transplant and maintained donor-derived hematopoiesis. Ten recipients had chimeric plasma PAF-AH genotypes between the donor-derived peripheral blood leukocytes and the recipient-derived epithelial cells of buccal mucosa. Multiple regression analysis demonstrated that PAF-AH activity in plasma depended on the donor's genotype (standardized regression coefficient = 0.68, P < 0.0001), but not on the recipient's genotype (p = 0.48). One recipient who was a V279F homozygote in leukocytes and wild type homozygote in buccal mucosa had undetectable PAF-AH activity in plasma. We conclude that most of the PAF-AH activity in human plasma originates from hematopoietic lineage cells.
Asano
K
K
Department of Medicine, Keio University School of Medicine, Tokyo, 160-8582, Japan. ko-asano@qa2.so-net.jp
Okamoto
S
S
Fukunaga
K
K
Shiomi
T
T
Mori
T
T
Iwata
M
M
Ikeda
Y
Y
Yamaguchi
K
K
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000328:Adult; D001483:Base Sequence; D016026:Bone Marrow Transplantation; D002610:Cheek; D002678:Chimera / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D005260:Female; D005838:Genotype; D006413:Hematopoietic System / Q000201:enzymology; D006801:Humans; D007962:Leukocytes / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D009061:Mouth Mucosa / Q000201:enzymology; D020125:Mutation, Missense; D010741:Phospholipases A / Q000096:biosynthesis / Q000097:blood* / Q000235:genetics; D010972:Platelet Activating Factor / Q000378:metabolism*; D014019:Tissue Donors; D014184:Transplantation, Homologous
D017931:DNA Primers; D010972:Platelet Activating Factor; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase