Suppressor T cells for delayed-type hypersensitivity to Japanese encephalitis virus

Area of Science:

• Immunology
• Virology
• T cell regulation

Background:

• Japanese encephalitis virus (JEV) infection can induce complex immune responses.
• Understanding immune regulation is crucial for controlling viral infections and hypersensitivity.
• Delayed-type hypersensitivity (DTH) is a key immune response to viral antigens.

Purpose of the Study:

• To investigate the role of suppressor cells in controlling delayed-type hypersensitivity (DTH) to Japanese encephalitis virus (JEV).
• To characterize the nature and function of suppressor cells involved in JEV infection.
• To determine the impact of suppressor cells on both cellular (DTH) and humoral (antibody) immune responses.

Main Methods:

• Induction of DTH in inbred Swiss mice following JEV infection.
• Transfer of immune spleen cells to assess suppressor activity.
• Treatment of spleen cells with anti-Thy-1.2 antisera and complement to identify cell types.
• Assessment of humoral response using direct antibody plaque-forming cell (IgM-PFC) assay.
• Evaluation of cyclophosphamide sensitivity of suppressor cells.

Main Results:

• JEV infection induced DTH peaking at day 7 and persisting for at least 119 days.
• Suppressor activity emerged on day 18, was transferable via immune spleen cells, and was abrogated by anti-Thy-1.2 treatment.
• Suppressor cells inhibited both DTH and IgM antibody production in an antigen-specific manner.
• Suppressor cells were sensitive to cyclophosphamide when administered 48 hours prior to their appearance.

Conclusions:

• JEV infection in mice generates antigen-specific suppressor T cells that regulate DTH.
• These suppressor T cells also modulate the T helper cell response for IgM antibody production.
• The suppressor cells are cyclophosphamide-sensitive and exert their function via soluble products.