Human interleukin 2. Quantitation by a sensitive radioimmunoassay.

Area of Science:

• Immunology
• Biochemistry
• Assay Development

Background:

• Accurate quantification of human interleukin-2 (IL-2) is crucial for understanding immune responses and therapeutic efficacy.
• Conventional IL-2 bioassays, while established, can be complex and may have limitations in sensitivity or throughput.
• Development of sensitive and reliable immunoassays is needed for routine IL-2 measurement.

Purpose of the Study:

• To develop and validate a sensitive radioimmunoassay (RIA) for the accurate quantitation of human interleukin-2 (IL-2).
• To assess the performance of the developed RIA in comparison to the conventional IL-2 bioassay.
• To evaluate the utility of the RIA for measuring IL-2 in clinical samples.

Main Methods:

• Development of a sandwich RIA using microtitration plates pre-coated with a specific anti-IL-2 monoclonal antibody (35H10).
• Quantification of captured IL-2 using a secondary rabbit anti-rIL-2 antibody and an 125I-labeled goat anti-rabbit IgG.
• Evaluation of assay sensitivity, correlation with IL-2 bioassay, and impact of serum/plasma inhibition.

Main Results:

• The developed RIA demonstrated high sensitivity, detecting as little as 100-200 pg/mL of human IL-2.
• Assay performance was comparable to the conventional IL-2 bioassay, showing good correlation in patient samples.
• Serum and plasma samples inhibited the assay, reducing sensitivity by approximately 5-fold, necessitating careful sample handling or dilution.

Conclusions:

• The developed radioimmunoassay provides a sensitive and reliable method for quantifying human IL-2.
• This RIA can serve as a valuable adjunct or alternative to the conventional IL-2 bioassay for analyzing IL-2 in various sample types.
• Further optimization may be needed to mitigate matrix effects observed with serum and plasma.