Anti-phosphatidylserine(anti-PS) monoclonal antibodies of the IgG isotype in the serum of normal Balb/c mouse were effectively induced by the intrasplenic immunization of phosphatidylserine 9PS0, while only a slignt increase of the titer was
observed
when the antigen was injected intravenousl. Among the fifteen monoclnal antibodies(mAbs0 examined, one mAb designated PSG3(IgG2b, k chain), showed a strong lupus anticoagulant, ss-DNA, ds-DNA binding and HUVEC(yhuman umbilical vein endothelial
cell)
binding activities. V region of the heavy chain of PSG3 was sequenced by a modification of Sanger's dideoxynucleotide method of DNA sequencing, using 5 crude mRNA as template, sypthetic oligonucleotides as primers and reverse transcriptase to
incorporat
both dideoxynucleotides and labeled deoxynucleotides. V region of the heavy chain of PSG3 showed high homology with J606 which recognized β(2→1) fructosan of bacteria membrane. It raises the possibility that IgG class anti-phospholipid antibody
(PSG30
is generated, by gene mutation, from B cells previously activated by bacteria.
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