Immunology: Key Concepts in Antigens, Antibodies, and Immune Response

Antigens

Foreign substances that induce a host response

Antigens

Elicit an immune response

Antibodies

A protein found in blood that is produced in response to a specific antigen

Immunity

Condition of being resistant to infection

Attenuation

Making a pathogen less virulent

Attenuation

Takes place through heat, aging, or chemical means

Innate Immunity

Also knowns as natural immunity

Innate immunity

the ability to resist infection by means of normally present body functions

innate immunity

Considered nonadaptive or nonspecific

Adaptive immunity

A type of resistance characterized by specificity for each individual pathogen, or microbial agents, and the ability to remember a prior exposure

Leukocytes

found in peripheral blood

Leukocytes

play a key role in both innate and adaptive immunity

Neutrophils

A type of white blood cell that engulfs invading microbes and contributes to the nonspecific defenses of the body against disease.

Eosinophils

type of white blood cell that plays a role in the immune system's response to infections, particularly parasites, and allergic reactions

Basophils

A circulating leukocyte that produces histamine.

Monocytes

An agranular leukocyte that is able to migrate into tissues and transform into a macrophage.

Lymphocytes

A type of white blood cell that make antibodies to fight off infections

Macrophages

Play a role in initiating and regulating innate and adaptive immune responses

Mast cells

Resemble basophils but come from a different lineage

Mast Cells

Can enhance and suppress the adaptive immune response

Dendritic Cells

Covered with long, membranous extensions that make them resemble nerve cell dendrites

Dendritic cells

Are considered the most effective APC in the body

Lymphocytes

Represent between 20% and 40% of the circulating WBCs

Bone Marrow

Main source of hematopoietic stem cells, which develop into erythrocytes, granulocytes, monocytes, platelets, and lymphocytes

Thymus

Location for maturation of T lymphocytes

Bone Marrow and Thymus

What are the two primary lymphoid organs?

Secondary lymphoid organs

Function as potential sties for contact sites for contact with foreign antigens

Secondary lymphoid organs

Increase the probability of an immune response

Spleen, lymph nodes, and MALT

What are the three secondary lymphoid organs

Spleen

Destroys old red blood cells

Primary follicles

Contains B cells not yet stimulated by antigens

Lymph nodes

General collecting points for lymph fluid

Lymph nodes

Lymphocytes and any foreign antigens enter nodes via afferent lymphatic vessels

Secondary follicles

Consist of antigen-stimulated proliferating B cells

Secondary follicles

Location where transformation of B cells takes places

MALT

Found on mucosal surfaces of the gastrointestinal, respiratory, and urogenital tracts

MALT

A main port of entry for foreign antigens

Intravenous

pertaining to within a vein

Intradermal

pertaining to within the skin

Subcutaneous

beneath the skin

Oral

pertaining to the mouth

Dose

The larger the amount of immunogen exposed to, the greater the immune response

Epitope

key portion of the immunogen recognized in the immune response

Linear epitopes

Epitopes composed of several successive amino acids in a protein sequence

Conformational epitope

Epitope that is recognizable in its 3D form by B Cells

Haptens

nonimmunogenic materials that, when combined with a carrier, create new antigenic determinants

Haptens

Contribute to the development of interconnected lattice that serves as the basis for precipitation and agglutination reactions

Adjuvants

Can make immunization more effective

Adjuvants

Works by targeting APCs

Adjuvants

Protect immunogens from degradation

Autoantigens

antigens on the surface of normal body cells

Alloantigens

cell surface markers and molecules that occur in some members of the same species but not in others

Heteroantigens

are from other species, such as other animals, plants, or microorganisms

Heterophile antigens

Exist in unrelated species, but their structure is so similar that antibody formed to one will cross-react with antigen from a different species

Major Histocompatibility Complex (MHC)

Linked to the genetic capability that allows the body to mount an immune response

Major Histocompatibility Complex (MHC)

Have been found on all nucleated cells in the body

Gene coding for MHC molecule

Found in humans on the short arm of chromosome 6

MHC Class I

found on three different loci (designated as A, B, and C)

MHC Class II

found on the D region (designated as DR, DQ, and DP)

MHC Class III

Found in a region between class I and II

MHC class I and II

are involved in antigen recognition

MHC class I and II

Influence the antigens to which T cells respond

MHC Class III

composed of secreted proteins that have an immune function, but they are not expressed on cell surfaces

Haplotype

area of linked genetic variations in the human genome

MHC Class I

Expressed on all nucleated cells

MHC Class I

Highest on lymphocytes and myeloid cells

MHC Class I

Lowest or undetectable on liver hepatocytes, neural cells, muscles, and spermatozoa

MHC Class I

Glycoprotein dimers made up of two noncovalently linked peptides

MHC Class II

Found primarily on APCs

B lymphocytes, monocytes, and macrophages

Examples of MHC Class Ii

MHC Class II

Two noncovalently bound peptides that are encoded by separate genes in the MHC complex

Class I MHC-peptide interactions

Transporters associated with antigen processing transporter antigenic peptides to the endoplasmic reticulum

Class II-MHC-peptide interaction

Molecules participate in the exogenous pathway of antigen presentation

MHC Class I and II

Can induce graft infection

Thymus

Pouch filled with lymphocytes

Bone marrow

T cells precursors leave the ____________ and travel to the thymus to mature into T cells

bone marrow

B cells remain in the ____ _______ for maturation

T cells

Which cells are used for cellular immune response

B cells

Which cells are used for humoral immune response

peripheral lymphoid organs

Cells leave thymus/BM and enter the blood stream and go into

lymph nodes

Located along lymphatic ducts going from tissues to thoracic duct and emptying into circulatory system

Lymph node

collecting joint

Afferent lymph ducts

carry lymph into gland

efferent lymph duct

carry lymph away from the gland

Cortical region

where B cells are found

Paracortical region

where T cells are found

lymph nodes

Filtering basin for infecting organisms

Antigen elimination

Process of removing antigens from the body.

three phases

How many phases are there in antigen elimination

Catabolic degradation/removal

enzymatic hydrolysis that occurs gradually

Immune elimination phase

New immunoglobulin combines with antigen and enhances phagocytosis and antigen removal

Primary response

first time the immune system combats a particular foreign substance

Secondary response

later interactions with the same foreign substance; faster and more effective due to "memory"

First injection

lag of several days following exposure

Antibody Synthesis

20 minutes are exposure

Lag period

Lasts anywhere from one to two weeks before detecting any circulating antibodies

IgG

Is made with secondary response

Placental transfer

Becomes especially important to consider when discussing secondary responses

Memory cells

Class of B cells that remain in circulation longer than plasma cells and do not secrete antibody until stimulated by antigen presentation in a secondary response

Innate defense system

Defenses against infection that immediately act when a host is attacked by a pathogen