Immunology & Serology Laboratory Theory

Comprehensive vocabulary flashcards covering fundamental immunology, cell-mediated vs humoral immune responses, antibody classes, vaccine types, hypersensitivity, and serological assays.

Antigen

A foreign substance (or carbohydrate/protein on its surface) capable of stimulating a specific immune response.

Immunity

Resistance to disease through the formation of antibodies, killer cells, and/or the release of substances that stimulate cells to develop antiviral properties.

Innate Immune System

The non-specific first line of internal defense consisting of fluid enzymes and phagocytic cells (macrophages and neutrophils) that scavenge foreign material.

Acquired Immune System

The adaptive internal defense system that produces a specific reaction to an infectious agent and establishes specific immunological memory.

Monocyte

A precursor cell in the blood that differentiates into a macrophage upon migrating into body tissues and organs.

Histiocytes

Macrophages that have migrated into specific tissues and organs to perform localized phagocytic functions.

Natural Killer (NK) Cells

T-cells that recognize cell surface changes on virally infected or neoplastic cells, bind to them, and destroy them.

Interferons

Substances produced by infected cells that activate NK cells and macrophages while inducing viral resistance in neighboring cells.

Complement System

Serum proteins activated by microorganism surfaces that interact to lyse invader cells, trigger chemotaxis, or cause opsonization.

Opsonization

The process of coating foreign cells with proteins (such as complement) to enhance phagocytosis by immune cells.

Inflammation

A localized protective response to injury characterized by heat, redness, swelling, pain, and loss of function, intended to destroy, dilute, or wall off invaders.

Chemotaxis

The process by which phagocytic cells are attracted to a site of inflammation.

B-cells

Bone marrow-derived lymphocytes of the humoral immune system that differentiate into antibody-secreting plasma cells or Memory B-cells.

Plasma Cells

Fully differentiated B-lymphocytes that secrete specific immunoglobulins (antibodies) into circulation.

Antibodies (Immunoglobulins)

Specific proteins produced by plasma cells that bind to antigens like a lock and key to neutralize them or trigger complement activation.

IgM

A systemic immunoglobulin constituting 20% of serum antibodies; it is the primary antibody produced in an initial immune response.

IgG

The primary systemic immunoglobulin constituting 80% of serum antibody protein; it crosses the placenta and passes via colostrum to transfer maternal immunity.

IgA

An immunoglobulin found in mucous membranes and non-vascular secretions such as saliva, bile, synovial fluid, and intestinal secretions.

IgE

An immunoglobulin involved in allergic and atopic reactions that binds to mast cells, triggering histamine and serotonin release.

IgD

An immunoglobulin class that functions primarily as an antigen receptor on B-cell surfaces.

T-cell Lymphocytes

Lymphocytes originating in bone marrow and maturing in the thymus that govern cell-mediated immunity.

T Helper-cells

T-lymphocytes that release cytokines upon antigen recognition to activate macrophages and assist B-cells in turning into plasma cells.

Killer T-cells

Cytotoxic T-lymphocytes that bind directly to virus-infected or foreign cells to cause their lysis, and mediate graft rejection.

Passive Immunity

Short-lived immunity acquired by transferring preformed antibodies into an animal, such as through colostrum or antitoxins.

Active Immunity

Long-term immunity developed by the animal's own immune system following natural exposure to environmental antigens or vaccination.

Colostrum

The initial milk secretion produced by the mother in the first 24–36 hours after birth, conveying 95% of initial passive immunity to neonates.

Adjuvant

A vaccine additive that enhances the immune response by slowing down the elimination rate of the antigen from the body.

Modified Live Vaccine

A vaccine made from attenuated microorganisms grown in vitro to lose disease-causing capability while retaining strong, long-lasting immunity stimulation.

Killed Vaccine

A vaccine consisting of inactivated microorganisms unable to replicate, providing a safer profile but shorter duration and weaker immune response.

Serology

The laboratory detection and measurement of antigens or antibodies present in blood serum.

Monoclonal Antibodies

Identical antibodies produced by hybrid cells formed by fusing plasma cells from hyperimmunized animals with immortal mouse myeloma cells.

ELISA (Enzyme Linked Immunosorbent Assay)

A diagnostic assay using bound monoclonal antibodies and an enzyme-labeled reagent to produce a color reaction identifying specific antigens or antibodies.

Immunodiffusion

A diagnostic technique where antigens and antibodies migrate through an agar gel matrix to form visible precipitation lines where they meet.

Latex Agglutination

A serologic assay using antibody- or antigen-coated latex beads that clump together upon contact with target serum antigens or antibodies.

Coombs' Test

A serologic test for immune-mediated hemolytic anemia (IMHA) that uses antiserum to detect autoantibodies or complement bound to red blood cells.

Autoagglutination

Spontaneous clumping of red blood cells indicative of IMHA, differentiated from rouleaux by mixing a drop of blood with saline.

Zinc Sulfate Turbidity

A quantitative in-house assay measuring the precipitation of serum globulins to estimate maternally derived IgG levels in neonatal foals and calves.

Titer

The highest serial dilution of serum at which a positive diagnostic reaction for an antibody or antigen can still be detected.

Seroconversion

The development of detectable specific antibodies in blood serum following exposure to an antigen or infectious agent.

Specificity

The probability that a test will correctly yield a negative result in uninfected animals, reflecting a low rate of false positives.

Sensitivity

The probability that a test will correctly identify all infected individuals, reflecting a low rate of false negatives.

Tuberculin Skin Test

A cell-mediated immunity assay where intradermal tuberculin injection produces local inflammation due to T-cell migration in exposed animals.