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Characterization of a monoclonal antibody with CD44 like reactivity

G Kremmidiotis1, G Russ, R Starr

  • 1Department of Clinical Immunology, Flinders Medical Centre, Flinders University of South Australia, Bedford Park.

Disease Markers
|January 1, 1991
PubMed

Insights

Monoclonal antibody QE7.3E8 initially appeared to target CD18 but showed distinct staining patterns. Further experiments confirmed QE7.3E8 reacts with the CD44 antigen, not CD18.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Biology

Background:

  • Monoclonal antibodies are crucial tools in immunology for identifying cell surface antigens.
  • QE7.3E8 is a monoclonal antibody with an observed immunoprecipitation pattern.
  • Initial characterization suggested QE7.3E8 might be a CD18 antibody.

Purpose of the Study:

  • To clarify the precise cell surface antigen recognized by the monoclonal antibody QE7.3E8.
  • To differentiate QE7.3E8 from known CD18 and CD11 antibodies.
  • To determine the expression profile and molecular interactions of the antigen targeted by QE7.3E8.

Main Methods:

  • Immunoprecipitation assays using B cell lines, monocytes, and T cell lines.
  • Tissue staining and distribution analysis.
  • Cross-immunoprecipitation experiments.
  • Sequential immunoprecipitation with QE7.3E8 and a known CD44 antibody (SBU 25-32).

Main Results:

  • QE7.3E8 precipitated different band patterns from B cells (90, 160 kd) and monocytes (90, 130, 146, 160 kd).
  • Tissue distribution of QE7.3E8 differed significantly from CD18 antibodies.
  • QE7.3E8 precipitated four bands from T cells lacking CD11b/CD11c alpha chains, inconsistent with CD18.
  • Cross-immunoprecipitation showed no association between QE7.3E8 and CD11a targets.
  • Sequential precipitation experiments indicated QE7.3E8 reacts with CD44, consistent with its known high molecular weight complexes.

Conclusions:

  • The monoclonal antibody QE7.3E8 does not recognize the CD18 antigen.
  • QE7.3E8 specifically targets the CD44 antigen.
  • The multiple bands observed in immunoprecipitation are likely due to CD44 complexes, not distinct molecules associated with CD18.

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