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Comparative analysis of human and macaque monkey CD4: differences in formaldehyde lability and conformation
1Tsukuba Primate Center for Medical Science, National Institute of Infectious Diseases, Ibaraki, Japan.
Experimental Animals
|March 14, 1998
Summary
Flow cytometry analysis reveals Nu-Th/i is superior to Leu-3a for macaque CD4 detection. Formaldehyde fixation impacts macaque CD4 staining, suggesting epitope conformational differences.
Area of Science:
- Immunology
- Primate Research
Background:
- CD4 is a crucial co-receptor for T-cell activation.
- Accurate CD4 characterization in non-human primates is vital for translational immunology research.
Purpose of the Study:
- To compare the efficacy of two monoclonal antibodies (mAbs), Leu-3a and Nu-Th/i, for characterizing macaque monkey CD4.
- To investigate the impact of fixation on CD4 staining in macaques versus humans.
Main Methods:
- Flow cytometry was employed to analyze macaque monkey CD4 expression.
- Monoclonal antibodies Leu-3a and Nu-Th/i were used for staining.
- Formaldehyde fixation effects were assessed on both macaque and human cells.
Main Results:
- Nu-Th/i demonstrated significantly higher fluorescence intensity compared to Leu-3a for macaque CD4 staining.
- Formaldehyde fixation markedly reduced fluorescence intensity for macaque CD4 stained with Leu-3a, but not human CD4.
- Epitope binding assays indicated differential antibody interactions with macaque CD4 compared to human CD4.
Conclusions:
- Nu-Th/i is the preferred antibody for reliable macaque CD4 analysis via flow cytometry.
- The Leu-3a epitope on macaque CD4 is conformationally cryptic or fragile, impacting antibody binding and detection.
- Amino acid substitutions in CD4 domain 1 may explain the observed differences in epitope characteristics between macaques and humans.