Helper T-cells, Cytotoxic T-cells, Clonal Selection, and MHC Proteins

What is the role of Helper T-cells?

Helper T-cells (CD4 cells) secrete interleukins to stimulate T-cells and B-cells. They attract macrophages, neutrophils, and NK cells to the infection site.

What is the role of Cytotoxic T-cells?

Cytotoxic T-cells (CD8 cells) kill infected or cancerous cells using perforins and granzymes. They also release interferons and TNF to fight viruses and tumors.

What is clonal selection?

Clonal selection is the process where immune cells (B or T cells) are activated and proliferate to fight a pathogen. The cells differentiate into effector cells (active) and memory cells.

What are effector cells?

Effector cells are the active immune cells that fight infections immediately, including helper T-cells, cytotoxic T-cells, and plasma B-cells.

What are memory cells?

Memory cells 'remember' pathogens for future immune responses, leading to faster and stronger responses on subsequent exposures.

What is MHC-I and its role?

MHC-I proteins are found on body cells and present endogenous antigens (from inside the cell) to cytotoxic T-cells (CD8 cells).

What is MHC-II and its role?

MHC-II proteins are found on antigen-presenting cells (APCs) like dendritic cells and macrophages. They present exogenous antigens (from outside the cell) to helper T-cells (CD4 cells).