Interferon as a mediator of human lymphocyte suppression

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Human suppressor cells, activated by concanavalin A (Con A), modulate immune responses.
• The precise mediators of Con A-induced suppression are not fully understood.
• Interferon (IF) is a cytokine with known immunomodulatory and antiviral properties.

Purpose of the Study:

• To investigate the role of interferon (IF) as a mediator of human concanavalin A (Con A) suppressor cell activity.
• To determine if IF production correlates with suppressor cell generation in various experimental settings.
• To ascertain if antiviral and suppressive activities are mediated by the same IF types.

Main Methods:

• Coculture of peripheral blood leukocytes (PBL) with Con A, tumor cell lines, or viruses.
• Assay of suppressor cell activity by measuring inhibition of mitogen responses.
• Quantification of interferon (IF) production and neutralization using anti-IF serum.
• Assessment of antiviral activity in cell-free supernatants.

Main Results:

• Addition of anti-human leukocyte IF serum abrogated Con A-induced suppressor cell activity.
• Coculture with certain virus-infected cells induced IF production and suppressor activity, which were neutralized by anti-IF serum.
• Exposure of PBL to purified protein derivative (PPD) induced both IF and suppressor activity in PPD-positive donors.
• Antiviral and suppressive activities of supernatants were consistently neutralized in parallel by anti-IF serum or acid pH treatment.

Conclusions:

• Interferon (IF) is a major mediator of human concanavalin A (Con A) suppressor cell activity.
• IF plays a significant role in immune suppression induced by various stimuli, including viral infections and certain antigens.
• The findings provide strong evidence for IF as a common mediator of both antiviral and suppressive functions in human lymphocytes.