Differential expression of alpha- and beta-defensins in human peripheral blood.
BACKGROUND
Human defensin peptides with broad-spectrum antimicrobial activity have been implicated in the human defence response towards microbial invasion. Two families of defensins designated alpha- and beta-defensins, respectively, have been identified. Little is known about the expression of both defensin families in human peripheral blood. The purpose of this study was to examine the expression of alpha- and beta-defensin genes in human peripheral blood.


METHODS
Fifty-one healthy blood donors were screened for defensin expression. Blood from defensin responders was stimulated by lipopolysaccharide or heat-inactivated Pseudomonas aeruginosa ex vivo. Levels of mRNA were assessed by semiquantitative RT-PCR. Southern blot analysis and sequencing were used to confirm the identity of defensin gene transcripts. Western blotting analysis was used to detect the expression of defensin peptides.


RESULTS
beta-defensin was undetected in human peripheral blood without stimulation. Following stimulation by lipopolysaccharide or heat-inactivated bacterial cells, the majority (88.2%) of healthy individuals had a detectable expression for beta-defensin-1 gene and 39.2% for beta-defensin-2 gene, compared with none for beta-defensin-3. beta-defensin-1 and -2 mRNAs in the stimulated human peripheral blood of responders became detectable at 3 h and showed a maximum at 6 h following induction by 100 ng mL-1 of lipopolysaccharide or bacterial cells. In contrast, human alpha-defensins 1-3 mRNA are constitutively expressed in peripheral leukocytes but not up-regulated by lipopolysaccharide or bacterial cells.


CONCLUSIONS
In human peripheral blood, beta-defensin-1 and -2 genes were transiently transcribed and translated following the induction of lipopolysaccharide or heat-inactivated bacterial cells, whereas alpha-defensins 1-3 genes were constitutively transcribed, and beta-defensin-3 gene was not expressed. The inducible expression of beta-defensin-1 and -2 genes showed interindividual variability.
Fang
X-M
XM
Sir Run Run Shaw Hospital, Zhejiang University, QingChun Road 3, 310016 HangZhou, Zhejiang, China. xm_fang@hotmail.com
Shu
Q
Q
Chen
Q-X
QX
Book
M
M
Sahl
H-G
HG
Hoeft
A
A
Stuber
F
F
D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007962:Leukocytes / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology; D011550:Pseudomonas aeruginosa / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023084:alpha-Defensins / Q000097:blood / Q000235:genetics*; D023083:beta-Defensins / Q000097:blood / Q000235:genetics*
D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D023084:alpha-Defensins; D023083:beta-Defensins