Unraveling the Mysteries of Self-Preservation
Immune Tolerance: T-Cells & B-Cells
By: Dr. Gregory Denomme PhD, FCSMLS (D)
Our immune system is a powerful defense against external threats like pathogens and foreign invaders. However, it must also distinguish between friend and foe, sparing our own tissues from attacks. This balance is achieved through immune tolerance, allowing immune cells to respond to dangers while coexisting peacefully with our bodies.
The Gatekeepers of Self-Recognition: T-Cell Immune Tolerance
T-cells, the versatile sentinels of our immune system undergo a selection process in the thymus. Those with a high affinity for self-antigens, markers of our tissues, are eliminated. This ensures T-cells entering the bloodstream can fight foreign invaders while avoiding attacks on our own cells.
Despite this selection, some foreign antigens may have epitopes that are similar to self-antigens, a phenomenon known as antigenic mimicry. This mimicry, along with other immune factors, can sometimes trick low affinity T-cells into attacking the body’s own tissues, contributing to autoimmune diseases.
The Guardians of Humoral Immunity: B-Cell Immune Tolerance
B-cells, essential for antibody production, also undergo a selection process in the bone marrow. Self-reactive B-cells are eliminated through a process called receptor editing. Low to moderate affinity self-reactive B-cells are not eliminated. These B-cells can react with foreign substances to ensure the immune system can respond to foreign threats.
The Adaptive Guardians: Regulatory T-Cells Modulate the Immune Response
Complementing the initial selection process, our immune system employs a specialized subset of T-cells known as regulatory T-cells (Tregs). These cellular sentinels help maintain immune balance by suppressing overactive T-cells. They produce immunosuppressive cytokines and modulate other immune cells, preventing autoimmunity.
The Interplay of T-Cells and B-Cells
While T-cells and B-cells play distinct roles in our immune defenses, their functions are intricately intertwined. T-cells not only provide critical signals that facilitate the activation and differentiation of B-cells but also exert regulatory control over their activity. This intricate collaboration ensures a harmonious balance between cellular and humoral immunity, allowing for a robust response against external threats while maintaining a peaceful coexistence with our own tissues.