Chapter 15: Immune Reactions to Antigens and the Activities of T cells

Flashcards created from the lecture notes on immune reactions to antigens, focusing on T cell activities and related concepts.

Antigen

A substance that induces an immune response, typically a foreign molecule.

Antigen-Presenting Cells (APC)

Cells that process and present antigens to T cells; includes macrophages, dendritic cells, and B cells.

MHC Class II

Major histocompatibility complex molecules that present processed antigens to CD4+ T cells.

CD4+ T Cells

A type of T cell that expresses CD4 receptors and regulates immune reactions to antigens.

Cytotoxic T (Tc) Cells

T cells that destroy virus-infected cells and cancer cells by secreting perforins and granzymes.

T Helper Cell 1 (TH1)

A subtype of CD4+ T cells that activate other T cells and are involved in delayed hypersensitivity.

Cytokines

Small proteins released by cells that have a specific effect on cell communication and behavior in immune responses.

Antigen Processing

The process by which APCs break down antigens into small peptides for T cell recognition.

Memory T Cells

Long-lived T cells that have previously encountered an antigen and can respond more quickly upon re-exposure.

Perforins

Proteins secreted by Tc cells that create pores in the membranes of target cells, facilitating their destruction.

Granzymes

Enzymes secreted by Tc cells that enter target cells through the pores created by perforins to induce apoptosis.

Th2 Cells

A subtype of CD4+ T cells that promote B cell proliferation and antibody production.

T Regulatory Cells (Treg)

T cells that help maintain immune tolerance and prevent autoimmunity by suppressing immune responses.

T Cell Receptor (TCR)

A molecule on T cells that recognizes and binds to specific antigens presented by MHC molecules.

CD28

A co-stimulatory molecule on T cells that binds to CD80 on APCs, providing necessary signals for T cell activation.