Generation of IgG Polymers by the Myeloperoxidase-H2o2-Catechol System and Their Stimulatory Effect on Oxygen Radical Production from Human Polymorphonuclear Leukocytes
Myeloperoxidase-H2o2-Catechol계에 의한 인체면역글로불린 G의 polymer 형성과 이들의 백혈구 산소라디칼 생성 촉진 효과
- Kim, Yong Sik; Chung, Myung Hee; Lim, Jung Kyoo
- Issue Date
- Seoul J Med, Vol.28 No.3, pp. 189-198
- Polymerization of native human IgG by myeloperoxidase (MPO)-H202-catechol
sytem and ability of the resulting polymers to stimulate polymorphonuclear neutrophils (PMNs)
to produce oxygen radicals were studied.
Incubation of the human IgG with PMN granules (as a source of MPO) and H202 in the
presence of catechol as a hydrogen donor resulted in polymerization of this protein, which was
confirmed by Sephacryl 200 column chromatography and polyethylene glycol precipitation
method. The polymer formation was completely abolished by omission of PMN granules,
H202 or catechol, and addition of catalase or azide to the complete system containing the
three components. Among the various hydrogen donors tested, only dopamine was able to
replace catechol in the polymerization (about 75% of that of catechol). The polymerization
was not affected by the quenchers for 0 ~, OH· or 102 and antioxidants but markedly
inhibited by benzenesulfinic acid and some compounds acting as a hydrogen donor. These
results suggest that the polymerization was due to oxidation of catechol to orthoquinone
mediated by MPO and H202 with ruling out the involvement of the oxygen radicals.
The IgG polymers obtained stimulated human PMNs to proudce O~ and H202 while
native IgG was much less effective in this respect. The stimulatory effect was even higher than
(about 1.5 times) that of heat-aggregated IgG having many properties similar to typical immune
complexes. Thus, it can be expected that the IgG polymers generated in the present
study will also behave as immune complexes in stimulation of PMNs.
The result was discussed in terms of a possible role of the IgG polymers in the pathogenesis
of tissue injury in many acute and chronic inflammatory conditions.