Conditioned immune response to interferon-gamma in humans

Area of Science:

• Immunology
• Neuroscience
• Behavioral Science

Background:

• Classical conditioning is a learning process where a neutral stimulus elicits a response after being associated with a stimulus that naturally elicits a response.
• Recombinant human interferon-gamma (rhIFN-gamma) is a cytokine known to stimulate immune responses.
• Propylene glycol (PG) is typically an immune-neutral substance.

Purpose of the Study:

• To investigate if classical conditioning can be used to elicit immunologic responses in humans.
• To determine if an immune-neutral stimulus (PG) can elicit an immune response after being paired with rhIFN-gamma.

Main Methods:

• A placebo-controlled, double-blind study was conducted with 31 healthy volunteers.
• Subjects were divided into three groups: rhIFN-gamma with PG, saline with PG, and rhIFN-gamma alone.
• Immune activation was assessed by measuring serum quinolinic acid (QUIN), neopterin, and Fc receptor (CD64) expression on peripheral blood mononuclear cells.

Main Results:

• rhIFN-gamma injections significantly altered immune parameters (QUIN, neopterin, CD64).
• Subjects receiving rhIFN-gamma and PG showed higher QUIN levels compared to rhIFN-gamma alone.
• The decline in neopterin levels was blunted in the rhIFN-gamma and PG group, and CD64 expression decline was also blunted.

Conclusions:

• Pairing rhIFN-gamma with PG allowed PG alone to prolong the cytokine-induced immune response.
• Classical conditioning may be a viable method to modulate immune responses in humans.
• This suggests a potential for using learned associations to influence physiological immune reactions.