Monoclonal anti-double stranded DNA antibody is a leucocyte-binding protein to up-regulate interleukin-8 gene expression and elicit apoptosis of normal human polymorphonuclear neutrophils.
OBJECTIVE
To determine whether anti-double stranded DNA (anti-dsDNA) autoantibody could bind and affect the functions of normal human polymorphonuclear neutrophils (PMN).


METHODS
Normal human PMN were incubated with different concentrations of a monoclonal mouse anti-dsDNA antibody (12B3) or mouse isotype-matched IgG2a. The binding of anti-dsDNA and PMN was measured by flow cytometry and interleukin-8 (IL-8) gene expression in PMN was detected by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR). PMN apoptosis was justified by morphological changes. The cognate antigen(s) of anti-dsDNA on the PMN surface was identified by membrane biotinylation, immunoprecipitation and Western blot.


RESULTS
The binding of PMN with anti-dsDNA was much higher than with non-specific mouse IgG2a (70.8 vs 2.0%). Anti-dsDNA at concentrations higher than 12.5 ng/ml significantly enhanced the production and mRNA expression of IL-8 by PMN. However, anti-dsDNA facilitated PMN apoptosis after 3 h incubation. Western blot analysis of biotinylated PMN cell lysates demonstrated that a 50-52 kDa membrane molecule is the cognate antigen of anti-dsDNA.


CONCLUSIONS
Anti-dsDNA autoantibody up-regulates IL-8 gene expression and elicits activation-induced cell death (AICD) of human PMN via binding to a 50-52 kDa membrane-expressed molecule.
Hsieh
S C
SC
Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.
Sun
K H
KH
Tsai
C Y
CY
Tsai
Y Y
YY
Tsai
S T
ST
Huang
D F
DF
Han
S H
SH
Yu
H S
HS
Yu
C L
CL
D000818:Animals; D000974:Antibodies, Antinuclear / Q000502:physiology*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D017209:Apoptosis; D002352:Carrier Proteins / Q000502:physiology*; D004247:DNA / Q000276:immunology*; D005786:Gene Expression Regulation; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics*; D051379:Mice; D009504:Neutrophils / Q000502:physiology*; D015854:Up-Regulation
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D016209:Interleukin-8; D004247:DNA