Appropriate fixative for MEM-G/9 staining of cultured human HLA-G-positive JEG-3 trophoblast tumor cells

Biotech Histochem. 2022 Feb;97(2):136-142. doi: 10.1080/10520295.2021.1916837. Epub 2021 Apr 29.


Human leukocyte antigen (HLA-G) participates in immunosuppression and is useful for prenatal diagnostics. Isolation of fetal cells positive for HLA-G by HLA-G antibody conjugated nanoparticles from the cervix of pregnant women is the basis for non-invasive prenatal testing. Endocervical specimens are fixed in transport medium before isolation using antibody conjugated nanoparticles. Staining of HLA-G using MEM-G/9 antibody, however, is restricted to unfixed cells. We investigated the effect of several fixatives on the interaction of HLA-G with MEM-G/9 in the HLA-G-positive cell line, JEG-3. We investigated absolute methanol, 1:1 acetate buffer:methanol, Pap solution and paraformaldehyde. The effects of these fixatives were evaluated using immunofluorescence. We found no MEM-G/9 surface staining of methanol fixed cells. Approximately 40% of JEG-3 cells fixed with paraformaldehyde failed to stain. Nearly all cells were stained with MEM-G/9 following fixation with acetate buffer:methanol or Pap solution. Our findings indicate the importance of using an appropriate fixative for preserving HLA-G cell surface antigen for studies using the MEM-G/9 antibody.

Keywords: Antibody; HLA-G; JEG-3 cells; MEM-G/9; fixative; human; immunocytochemistry; trophoblast tumor.

MeSH terms

  • Cell Line, Tumor
  • Female
  • Fixatives
  • HLA-G Antigens*
  • Humans
  • Pregnancy
  • Staining and Labeling
  • Trophoblastic Neoplasms*


  • Fixatives
  • HLA-G Antigens