The path of a Killer T cell 

First stage:

also known as cytotoxic T cells, are immune cells that destroy infected or abnormal cells by releasing toxic substances

Recognition, Attack, Signaling, Memory

Antigens: Molecules that trigger an immune response and can be produced by viruses, bacteria, cancer cells, or intracellular signals

T-cell receptors (TCRs): Receptors on the surface of killer T cells that bind to specific antigens

Major histocompatibility complex (MHC) Class I molecules: Molecules on the surface of cells that present antigens to T cells

CD8 receptors: Receptors on the surface of killer T cells that interact with MHC Class I molecules

killer T cells release perforin and granzymes to kill the infected cell

Killer T cells use cytokines to send chemical instructions to the rest of the immune system to increase its response

The signal for a killer T cell response is the binding of the T cell receptor (TCR) and CD8 on the killer T cell to the MHC/Epitope on the surface of a virus-infected cell. This binding triggers a series of events that result in the infected cell's destruction

The granules in the killer T cell release perforins, granzymes, and chemokines.

The perforins polymerize to create pores in the infected cell's membrane

The granzymes activate caspases, which destroy the cell's cytoskeleton, nucleoprotein, and DNA

When the body is first exposed to a pathogen, rare T cells that are specific to that antigen expand rapidly. However, most of these cells are eliminated, leaving a small number that survive to become memory T cells.

When the body encounters the same pathogen again, the memory T cells quickly expand into large numbers of effector T cells. This rapid response, along with antibody responses, can quickly eliminate the pathogen

There are different subtypes of memory T cells, including central memory T cells (Tcm cells) and effector memory T cells (Tem cells and Temra cells)

Second stage:

Macrophages

Macrophages eat other cells and are able to pull apart their proteins in order to present them to T cells.

Phagocytosis

The seven steps of phagocytosis are:

Detection: Phagocytic cells use receptors to detect the target particle

Binding: The receptors bind to foreign substances, such as antibodies that have marked a pathogen

Engulfment: The cytoplasm engulfs the bound pathogen through endocytosis

Phagosome formation: The engulfed particle is enclosed in a bubble-like structure called a phagosome

Phagosome-lysosome fusion: The phagosome fuses with a lysosome to become a phagolysosome

Digestion: Enzymes in the lysosomes digest the food particle

Exocytosis: Remnants are propelled out through exocytosis

The cell membrane extends projections called pseudopodia around the particle. 

The pseudopodia fuse to form a vesicle called a phagosome

The phagosome matures by fusing with endosomes and lysosomes, becoming a phagolysosome

The phagolysosome's hydrolytic enzymes break down the particle

The path of a B-Lymphocyte

 B lymphocytes originate from hematopoietic stem cells

Hematopoietic stem cells give rise to different types of blood cells, in lines called myeloid and lymphoid. Myeloid and lymphoid lineages both are involved in dendritic cell formation

Types of myeloid cells include Granulocytes a type of white blood cell that includes neutrophils, eosinophils, and basophils

Enzymes in neutrophil granules include:

Neutrophil serine proteases (NSPs): 

NSPs kill bacteria directly, and are involved in the non-oxidative mechanism of bacterial killing

These enzymes include cathepsin G (CG)

Cleaves and inactivates chemoattractants

Cathepsin G breaks down components of the extracellular matrix

Cathepsin G activates matrix metalloproteinases, which degrade the extracellular matrix

neutrophil elastase (NE)

NE can promote tumor growth by remodeling the tumor microenvironment and promoting metastasis

and proteinase 3 (PR3)

breaks down proteins

myeloid cells are involved in bacterial defense and regulating inflammation

Eosinophils help maintain homeostasis in the body

homeostasis is the ability to maintain a relatively stable internal state that persists despite changes in the world outside

Basophils release histamine

Basophils release heparin to prevent blood clots from forming in areas where there is damage

Basophils are a major source of IL-4, a cytokine that links innate and adaptive immunity

The B lymphocytes that respond to an infection mature into plasma cells. These plasma cells make and release immunoglobulins, also called antibodies

B cells use their B cell receptors (BCRs) to identify a specific protein, or antigen, on a pathogen

Protein antigens are broken down into peptide epitopes

Peptide epitopes bind to MHC II molecules

B cell activation: The BCR, MHC II complex, and TCR interact, activating helper T cells and releasing cytokines

Activated B cells differentiate and produce antibodies

Activated B cells create memory cells

Lucy’s Experience

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Harlow’s Experience

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Asparagine: A polar amino acid that's involved in protein synthesis, nucleotide biosynthesis, and regulating the uptake of other amino acids

Dalton’s Experience 

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