Proliferation assay amplification by IL-2 in model primary and recall antigen systems

Area of Science:

• Immunology
• Cellular Biology

Background:

• Detecting weak T lymphocyte proliferation to antigens is challenging in standard peripheral blood mononuclear cell (PBMC) cultures.
• Interleukin-2 (IL-2) is a cytokine known to influence T cell responses.

Purpose of the Study:

• To evaluate the effectiveness of IL-2 in amplifying T lymphocyte proliferative responses.
• To determine the optimal timing for IL-2 addition to enhance antigen-specific T cell assays.

Main Methods:

• PBMCs from healthy donors were cultured with keyhole limpet hemocyanin (KLH) or tuberculin PPD.
• IL-2 was added either at the start of culture or on day five.
• Tritiated thymidine incorporation was used to measure proliferation at day eight.

Main Results:

• Early IL-2 addition caused high proliferation, even without antigen.
• Late IL-2 addition (day five) enabled clear detection of KLH-induced T cell proliferation.
• Late IL-2 also boosted responses to PPD, LPS, and poly(I:C) but not PWM.

Conclusions:

• Late addition of IL-2 significantly increases the sensitivity of T lymphocyte proliferation assays.
• This strategy allows for the reliable observation of low-level T cell responses to specific antigens.