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Updated: Aug 8, 2026
Analysis of Cell Cycle Position in Mammalian Cells
Published on: January 21, 2012
Cell cycle-dependent expression of CD4 antigen in a monocytoid cell line
C F Martin1, J Correale, S Kam-Hansen
1Department of Virology, Central Microbiological Laboratory of Stockholm County Council, Sweden.
Insights
Cell cycle influences CD4 molecule expression. Researchers found that CD4 reappearance and expression levels peak during the S and G2 phases, indicating cell cycle-dependent regulation of this important cell surface protein.
Area of Science:
- Immunology
- Cell Biology
Background:
- The CD4 molecule serves as a receptor for MHC class II molecules and a co-receptor for HIV entry.
- CD4+ T-cell counts are critical indicators of HIV infection progression and disease severity.
Purpose of the Study:
- To investigate whether CD4 molecule expression and density vary across different phases of the cell cycle.
- To analyze the cell cycle-dependent regulation of CD4 surface expression.
Main Methods:
- Synchronization of a CD4-expressing monocytoid cell line (U 937 clone 16) for cell cycle analysis.
- Quantification of CD4 antigen expression, density, and reappearance rate after trypsinization during distinct cell cycle phases.
Main Results:
- The rate of CD4 molecule reappearance on the cell surface was highest during the S phase of the cell cycle.
- Increased CD4 expression and density were observed in the late S/G2 phases.
Conclusions:
- CD4 molecule expression on the cell surface is regulated in a cell cycle-dependent manner.
- These findings provide insights into the dynamic regulation of CD4 expression, potentially impacting HIV interactions.
Abstract:
The CD4 molecule has several biological functions, physiologically as a receptor for major histocompatibility complex class II molecules on antigen-presenting cells, and pathologically as a receptor for human immunodeficiency virus (HIV) by its binding to the HIV envelope glycoprotein gp 120. The frequency of CD4+ cells has been shown to correlate positively with both susceptibility and cytopathogenic effect by HIV. To determine if CD4 expression varied during the cell cycle, a CD4-expressing monocytoid cell line, U 937 clone 16, was synchronized with regard to cell growth. The CD4 antigen was analysed with regard to expression, density and rate of reappearance after treatment with trypsin, during the different phases of the cell cycle. The CD4 reappearance rate was found to be maximal during the S phase. This was followed by an increased expression and density in the late S/G2 phase. Thus a cell cycle-dependent expression of CD4 molecules on the cell surface was observed.
