Immunology - Self and non-self recognition

What is an innate immune system?

- Non specific, no memory, fast (hrs), constant, use a few receptors to recognize things in common among pathogens. - Barrier defenses (mechanical, chemical, biologic are considered part of the innate immune system) - Responds in the same way no matter how many times you are exposed to the antigens Ex: NK cells, Dendritic cells, macrophages, mast cells

Antibody cross-reactivity

- Occurs when antigens are shared or similar in structure - If you get infected by Rhinovirus strain 16 (cold virus) - you make a strong antibody response, but if someone with strain 202 sneezes on you, then you will not feel stratchy throat for alittle but then not get sick because of the structurally similar antibodies.

What is the basis of immune memory?

Adaptive immune system: B cells & T cells

What is a multivalent antigen?

Antigen containing more than one epitope. Can be different kinds of epitopes or identical.

How does B cell know how to make antibodies to a specific pathogen like HIV and not E.Coli?

Because specificity is determined before contact with the antigens.

T lymphocytes (cells)

Cell mediated immunity - kills infected cells, secretes cytokines, and activates phagocytes and other T and B cells Two different kinds of T cells: - Helper T cells: Eliminate phagocytose microbes - Killer T cells (Cytotoxic T lymphocytes): Kill infected cells and eliminate reservoirs of infections.

Where are non-self antigens found?

Found on pathogens (micro-organisms that cause infectious diseases) and allergens (provoke allergic responses)

What are haptens?

Haptens are a special class of antigens which are only immunogenic when attached to a larger molecule called a carrier. Too small by themselves to provoke a immune cell. Ex: nickel ions- remember allergies to cheap jewelry - BOUJIE AF

What is an adaptive immune system?

Highly specific, has memory, slow (days), improves over time, uses unique receptors to recognize unique things among pathogens. Two types of adaptive immunity: Humoral immunity and cell-mediated immunity - mediated by B and T lymphocytes. functions: block infections and eliminate extracellular microbes, eliminate phagocytosed microbes, kill infected cells and eliminate reservoirs of infections With more exposure, improves over time, and gets stronger, and the ligand to receptor binding is stronger and gets more productive. Ex: T and B cells

B cell

Humoral immunity (in the blood) secrete antibodies and present antigens; effector mechanisms.

What are the major components of the adaptive immunity?

Humoral immunity and cell mediated immunity mediated by T cells and B cells - Receptors : TCR (T cell receptors) found on t cells and Immunoglobulin (antibodies) found on and secreted by B cells

Mast cells (yellow)

Inflammatory responses, innate immunity, anti-helminth immunity

How does the innate immune system differ from the adaptive immune system?

Innate immune system is Non specific, no memory, fast (hrs), constant, use a few receptors to recognize things in common among pathogens, while Adaptive immune system is Highly specific, has memory, slow (days), improves over time, uses unique receptors to recognize unique things among pathogens.

What are the basic characteristics of a good antigen?

Large> small; Proteins > carbs> lipids; dosage: intermediate >> small, large

Myeloid cells

Macrophages or monocytes: phagocytic cells which present antigens Dendritic cells also present antigens

Granulocytes

Neutrophils - phagocytic cells, gray staining granules - body's trash man; Eosinophils - anti-helminth (roundworms and tapeworms) and Basophils - infiltrate skin lesions

What are the key organs of the immune system?

Primary organs: bone marrow, thymus and secondary organs: spleen, lymph nodes, peyers patches, tonsils

Where do all cells of the immune system derive for a single pluripotent, self-renewing precursor?

Stem cell CD34+ - These cells are to be replaced in the patients who have leukemia if they have CD34 in the bone marrow.

What are the effective routes of antigen delivery into the body?

Subcutaneous, intramuscular > intraperitoneal > IV > Oral

What are the cellular and molecular components of the immune system?

T and B cells, and immunoglobulin (antibodies) secreted by B cells and T cell receptors found on T cells.

What is an immunogens

agents that provoke immune responses (Ex. Virus, a worm,) : it triggers an immune response.

FC receptors (yellow)

bind Fc regions of antibodies - found on multiple immune cells Pattern recognition receptors - initiate innate immune responses

What is the difference between conformational and linear epitopes?

different kinds of epitopes: Conformational epitopes is for proteins; 3 dimensional shape which most antibodies recognize Linear epitopes is for bacterial cell walls; recognized by antibodies by its linear sequence

Immunoglobulin (IG) or antibodies -

found on and secreted by B lymphocytes

NK cells

large granular lymphocytes that kill tumor and virus infected cells. Not part of the adaptive immune system.

How do immune cells traffic?

lymphocytes enter lymph nodes via afferent lymphoid vessels or from the artery to high endothelial venue to the lymph node to blood vessels to peripheral tissues They leave from the efferent vessels.

Anaphylaxis

overreaction of the immune system.

Antigens

things the immune system specifically reacts with (ex. Influenza) Can be "self" in terms of autoimmune diseases

Epitopes or antigenic determinants:

what antibodies and T cells physically bind to