Lymphocyte- a form of small leukocyte (white blood cell) with a single round nucleus, occurring especially in the lymphatic system.

Dendritic Cells- are antigen-presenting cells. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system.

T-cell- a  lymphocyte that develops from stem cells in the bone marrow and matures in the thymus gland.

Naïve T-Cell (Th0)- a T-cell that has not encountered an antigen within the periphery.

Allergen- An allergen is any substance (antigen) that is recognized as an invader by the immune system and causes an allergic reaction.

Antigen- a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies. - Oxford

Interleukin-4 (IL4)- IL-4 is a cytokine that functions as a potent regulator of immunity secreted primarily by mast cells and Th2 cells.

Cytokines- abroad and loose category of small proteins released by many different cells in the body, including those of the immune system where they coordinate the body's response against infection and trigger inflammation.

T-helper-2 (Th2)- T-lymphocytes that mediate the activation and maintenance antibody-mediated immune responses against extracellular parasites, bacteria, allergens, and toxins.

B-cell- a lymphocyte not processed by the thymus gland, and responsible for producing antibodies.

Plasma Cell- a fully differentiated B cell that produces a single type of antibody.

Immunoglobulin aka Antibody- A protein produced by plasma cells and lymphocytes.

Immunoglobulin E (IgE)- an antibody produced during allergic reactions.

Mast Cell- a cell containing granules that are rich in histamine, heparin, and other inflammatory mediators.

Inflammatory Mediator- a chemical messenger that acts on blood vessels and/or cells to promote an inflammatory response.

Prostaglandins (PG)- a group of lipid compounds called eicosanoids having diverse hormone-like effects.

Leukotrienes- a family of eicosanoid inflammatory mediators produced in white blood cells by the oxidation of the fatty acids arachidonic acid (AA) and the eicosapentaenoic acid (EPA)

Protease- an enzyme that breaks down proteins into smaller polypeptides or single amino acids by hydrolysis.

Heparin- produced by mast cells and basophils.  Acts as an anticoagulant (blood thinner), which can prevent of break up blood clots.

Nitric Oxide- dilates blood vessels, increasing blood flow and lowering blood pressure.

Reactive Oxygen Species- an unstable molecule that contains oxygen and that easily reacts with other molecules in a cell.

Free radicals- unstable atoms that can damage cells

Monoamine oxidase (MAO)- an enzyme that breaks down neurotransmitters including histamine.
 
SOURCES
Seminar: “TREATING THE HYPERVIGILANT IMMUNE SYSTEM: HISTAMINE”, February 2018,  by Kerry M. McCord, DC, DIBAK and Walter H. Schmitt, DC, DIBAK, DABCN
https://en.wikipedia.org/wiki/Adaptive_immune_system
https://en.wikipedia.org/wiki/T_helper_cell
https://www.sciencedirect.com/topics/neuroscience/cytokines