Stigma variations: observations on suppressor T cells and leprosy

Area of Science:

• Immunology
• T cell subsets
• Immunoregulation

Background:

• The role of suppressor T cells in immunology has been a long-standing controversy.
• Functional human T cell subsets (CD4 and CD8) have been delineated through studies of infectious diseases and allergies.
• These subsets differ in their functions and lymphokine production patterns.

Purpose of the Study:

• To delineate functional human T cell subsets.
• To characterize T suppressor clones in leprosy patients.
• To discuss models of peripheral tolerance based on T cell subsets.

Main Methods:

• Analysis of T cell clones from patients with infectious diseases (leprosy) and allergies.
• Discrimination of CD4 and CD8 cell subsets based on function and lymphokine profiles.
• Characterization of T suppressor clones for antigen specificity, CD8 marker, HLA restriction, and lymphokine production.

Main Results:

• Type 1 CD4 cells (lepromin/PPD reactive) produce IFN-gamma and IL-2.
• Type 2 CD4 cells (tetanus toxoid reactive) produce IL-4 and IL-5.
• Type 1 CD8 cytotoxic T lymphocytes produce IFN-gamma and IL-2.
• T suppressor clones from lepromatous leprosy patients are antigen-specific, CD8+, HLA-DQ restricted, and produce IL-4, designated Type 2 CD8 cells.

Conclusions:

• Distinct functional T cell subsets (Type 1 and Type 2) exist within both CD4 and CD8 populations.
• Type 2 CD8 cells represent antigen-specific suppressor T cells involved in peripheral tolerance.
• Models of T cell suppression and peripheral tolerance can be reinterpreted based on these functional T cell subset interactions.