Principles of Immunology

Vocabulary flashcards covering the historical milestones, anatomical structures, cellular components, and molecular mechanisms of immunology.

Edward Jenner

Physician credited with establishing the method of vaccination against natural smallpox at the end of the $XVIIIth$ century.

I.I. Mechnikov

Scientist who formulated the phagocytic theory of immunity in $1887$.

P. Ehrlich

Scientist who proposed the humoral theory of immunity in $1901$.

M.F. Bernet

Scientist who developed the clone-selection theory of immunodefence and termed lymphocytes as immunocytes.

Primary Lymphoid Organs

Organs such as the bone marrow and thymus where lymphocyte maturation occurs independent of foreign antigens.

Secondary Lymphoid Organs

Organs including the spleen, lymph nodes, and Peyer's patches where immune responses to antigens take place.

Thymocytes

Developing $T-cells$ located within the cortex and medulla of the thymus.

Hassal's Corpuscles

Structures in the thymic medulla composed of concentrated whorls of mature keratinized epithelium.

Haptens

Low molecular weight substances, typically less than $10,000\,kD$, that become immunogenic only when bound to a carrier protein.

Epitope

The specific antigenic determinant on a molecule that is recognized by an immunoglobulin or T-cell receptor.

Ig M

A polymeric antibody that constitutes approximately $10\%$ of serum immunoglobulins and initiates early primary immune responses.

Ig G

The predominant monomeric antibody in normal adults, making up about $75\%$ of serum antibodies and capable of crossing the placenta.

Monoclonal Antibodies

Highly specific antibodies derived from a single clone of plasma cells, often used in diagnostics and cancer treatment.

Major Histocompatibility Complex

A genetic segment on chromosome $6$ encoding cell surface antigens essential for tissue graft recognition and immune regulation.

MHC Class I Antigens

Surface molecules expressed on all nucleated cells that interact with $CD8^+$ cytotoxic $T-lymphocytes$.

MHC Class II Antigens

Surface molecules on antigen-presenting cells that interact with $CD4^+$ T-helper cells to initiate immune responses.

Cytokines

Low-molecular-weight proteins that serve as intercellular messengers to regulate inflammatory and immune reactions.

Interferons

Species-specific proteins with strong antiviral and antitumor activities that prevent viral replication.

Complement System

A cascade of over $25$ serum proteins that provide humoral protection through lysis, opsonization, and inflammation.

NK Cells

Large granular lymphocytes that destroy tumor or virus-infected cells without the requirement for $MHC$ restriction.

PAMPs

Conserved molecular patterns on pathogens, such as flagellin and peptidoglycan, that are recognized by the innate immune system.

Toll-Like Receptors

A set of $11$ different membrane receptors that identify specific pathogen patterns to trigger effector responses.

Phagocytosis

The multi-step process including chemotaxis, adhesion, and ingestion performed by cells like neutrophils and macrophages to destroy foreign agents.

Allografts

Tissue or organ transplants performed between two genetically distinct individuals of the same species.

Rh Factor

A Rhesus system antigen discovered in $1940$ that is present on the red blood cells of approximately $85\%$ of the human population.