CD23 expression in activated human T cells is enhanced by interleukin-7

Area of Science:

• Immunology
• Cell Biology

Background:

• The role of Fc epsilon RII/CD23 in normal human T cells remains unclear despite its expression in pathological conditions.
• Interleukin-7 (IL-7), a stromal-derived cytokine, is investigated for its effect on CD23 expression in T cells.

Purpose of the Study:

• To investigate the effect of IL-7 on CD23 expression in phytohemagglutinin (PHA)-stimulated human T cells.
• To determine if IL-7 modulates CD23 expression independently of other cytokines like IL-2 and IL-4.

Main Methods:

• Human T cells were stimulated with PHA and costimulated with IL-7.
• Cytofluorometric analysis was used to quantify CD23 expression.
• Northern blot and Scatchard analysis were employed to assess mRNA levels and receptor numbers.
• Monoclonal antibodies against IL-7, IL-2, and IL-4 were used to block cytokine effects.

Main Results:

• IL-7 did not induce CD23 expression on resting T cells but significantly enhanced PHA-induced expression on activated T cells (from 2% to 18%).
• The effect of IL-7 was specific to CD4+ T cells and was blocked by an anti-IL-7 mAb, indicating independence from IL-2 and IL-4.
• IL-7 increased CD23 mRNA levels and receptor numbers on activated T cells, with a greater magnitude than other tested cytokines.

Conclusions:

• IL-7 is a potent regulatory cytokine that selectively induces CD23 expression on activated human T cells.
• CD23 likely plays a significant role in the regulatory network of the immune response, influenced by IL-7.