Cell-mediated Immunity (CMI)
Immunity mediated by T-lymphocytes, responsible for rejecting foreign grafts and eliminating infected cells.
What is Cell-mediated Immunity (CMI)?
A type of adaptive immunity that involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of cytokines and lymphokines in response to an antigen.
Key points
- Explain the mechanism of cell-mediated immunity.
- Differentiate between the roles of cytotoxic T-cells and helper T-cells.
- Describe how CMI combats intracellular pathogens and cancer cells.
- Understand the role of CMI in transplant rejection.
Common exam trap
Confusing CMI with humoral immunity (antibody-mediated).
Definitions
- Term
Cell-Mediated Immunity (CMI)
- Meaning
A type of adaptive immunity that involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of cytokines and lymphokines in response to an antigen.
- Term
Cytotoxic T-lymphocyte (CTL)
- Meaning
A T-lymphocyte that kills cancer cells, cells infected with viruses, and foreign cells during tissue transplantation.
- Term
Helper T-cell (Th)
- Meaning
A type of T-lymphocyte that plays a central role in the immune system by activating B-cells to secrete antibodies and other T-cells that help kill infected cells.
- Term
Perforin
- Meaning
A protein, released by cytotoxic T-cells and natural killer cells, that polymerizes to form pores in the membranes of target cells.
- Term
Granzymes
- Meaning
A group of serine proteases released by cytotoxic T-cells and natural killer cells that induce apoptosis in target cells.
- Term
Apoptosis
- Meaning
Programmed cell death, a normal process that eliminates unwanted or harmful cells.
Learning objectives
Explain the mechanism of cell-mediated immunity.
Differentiate between the roles of cytotoxic T-cells and helper T-cells.
Describe how CMI combats intracellular pathogens and cancer cells.
Understand the role of CMI in transplant rejection.
Prerequisites
Basic understanding of the immune system.
Knowledge of lymphocytes (B-cells and T-cells).
Understanding of antigens and antibodies.
Concept of Major Histocompatibility Complex (MHC).
Common mistakes
Confusing CMI with humoral immunity (antibody-mediated).
Not distinguishing between the roles of different T-cell subsets (cytotoxic, helper, suppressor).
Forgetting the role of MHC molecules in antigen presentation to T-cells.
Underestimating the importance of CMI in transplant rejection.
Keywords
Cell-Mediated Immunity
T-lymphocytes
Cytotoxic T-cells
Helper T-cells
Thymus
MHC Class I
MHC Class II
Perforin
Granzymes
Apoptosis
Transplant Rejection
Intracellular Pathogens
Practice preview
Which of the following cells are primarily responsible for cell-mediated immunity?…
easy
Graft rejection is primarily mediated by which component of the immune system?…
medium
Cell-mediated immunity is crucial for defending the body against:…
easy