English for Immunology: Essential Vocabulary & Phrases

"pathogen-associated molecular pattern (PAMP)"

a conserved molecular structure found on pathogens that is recognised by receptors of the innate immune system

"Lipopolysaccharide is a classic PAMP that activates macrophages upon bacterial infection."

"toll-like receptor (TLR)"

a class of pattern recognition receptor on innate immune cells that detects PAMPs and triggers inflammatory responses

"TLR4 recognises bacterial lipopolysaccharide and initiates NF-κB-dependent gene transcription."

"phagocytosis"

the process by which immune cells engulf and destroy pathogens, dead cells, or debris by internalising them into a phagosome

"Neutrophils rapidly migrate to infection sites where they eliminate bacteria via phagocytosis."

"neutrophil"

the most abundant circulating white blood cell and a key effector of innate immunity, specialised in phagocytosis and degranulation

"A neutrophil count below 500 cells/µL places a patient at high risk of serious bacterial infection."

"macrophage"

a large phagocytic cell derived from monocytes that engulfs pathogens, presents antigens, and orchestrates inflammatory responses

"Activated macrophages secrete tumour necrosis factor-alpha to amplify the local inflammatory response."

"natural killer (NK) cell"

an innate lymphoid cell that destroys virally infected and tumour cells without prior antigen-specific sensitisation

"NK cells recognise targets by detecting the absence of self MHC class I molecules."

"complement system"

a cascade of serum proteins that enhance antibody-mediated immune responses, promote inflammation, and directly lyse pathogens

"The complement system can be activated via classical, lectin, or alternative pathways, all converging at C3."

"interferons"

signalling proteins released by cells in response to viral infection that induce an antiviral state in neighbouring cells

"Type I interferons upregulate MHC class I expression and restrict viral replication across surrounding tissue."

"clonal selection"

the process by which a specific lymphocyte bearing an antigen receptor that matches the invading antigen is selected and undergoes rapid proliferation

"Clonal selection ensures that only the B cell clones bearing receptors for the target antigen expand during an infection."

"MHC (major histocompatibility complex)"

a set of cell-surface proteins essential for the immune system to recognise foreign molecules; divided into class I and class II

"CD8+ T cells recognise peptide antigens presented by MHC class I molecules on virtually all nucleated cells."

"antigen presentation"

the process by which antigen-presenting cells display peptide fragments on MHC molecules for recognition by T lymphocytes

"Professional antigen-presenting cells such as dendritic cells are highly efficient at antigen presentation to naïve T cells."

"T helper cell (Th cell)"

a CD4+ T lymphocyte that activates other immune cells by releasing cytokines, coordinating both cellular and humoral immune responses

"Th1 cells promote cell-mediated immunity by secreting IFN-γ to activate macrophages and cytotoxic T cells."

"cytotoxic T lymphocyte (CTL)"

a CD8+ T cell that directly kills target cells displaying foreign peptides on MHC class I, using perforin and granzymes

"Cytotoxic T lymphocytes eliminate virally infected hepatocytes during chronic hepatitis B infection."

"immunological memory"

the ability of the immune system to mount a faster and stronger response upon re-exposure to a previously encountered antigen

"Immunological memory is the immunological basis for the protective efficacy of vaccination."

"dendritic cell"

a professional antigen-presenting cell that captures antigens in peripheral tissues, matures, and migrates to lymph nodes to prime naïve T cells

"Plasmacytoid dendritic cells produce large quantities of type I interferons in response to viral nucleic acids."

"regulatory T cell (Treg)"

a specialised CD4+ T cell subset that suppresses excessive immune responses to maintain self-tolerance and prevent autoimmunity

"Depletion of regulatory T cells in tumour-bearing mice dramatically enhances anti-tumour immunity."

"immunoglobulin (Ig)"

a glycoprotein produced by plasma cells that functions as an antibody; structured as two heavy chains and two light chains

"Serum immunoglobulin G levels are routinely measured to assess a patient's humoral immune status."

"B cell receptor (BCR)"

the membrane-bound antigen receptor on B lymphocytes, consisting of a surface immunoglobulin associated with signalling subunits Igα and Igβ

"Cross-linking of the B cell receptor by multivalent antigens initiates downstream signalling cascades."

"somatic hypermutation"

the process of rapid accumulation of mutations in immunoglobulin variable region genes within germinal centres to generate antibodies with higher affinity

"Somatic hypermutation in germinal centres drives affinity maturation of the antibody response over several weeks."

"class switching (isotype switching)"

the process by which a B cell changes the heavy-chain constant region of its immunoglobulin, producing antibodies of a different isotype with the same antigen specificity

"IL-4 signalling promotes class switching from IgM to IgE, driving allergic sensitisation."

"plasma cell"

a terminally differentiated B lymphocyte that secretes large amounts of antigen-specific antibodies

"Long-lived plasma cells residing in bone marrow niches maintain circulating antibody titres for decades."

"epitope"

the specific site on an antigen to which an antibody or T cell receptor binds; also called an antigenic determinant

"Broadly neutralising antibodies target conserved epitopes on the influenza haemagglutinin stem region."

"affinity maturation"

the process during an immune response in which B cells with higher affinity antibodies are selectively expanded through somatic hypermutation and germinal centre selection

"Affinity maturation occurs in germinal centres and results in antibodies up to 10,000-fold more potent than the initial response."

"monoclonal antibody (mAb)"

an antibody produced by a single B cell clone, making it monospecific and identical in structure, widely used as a therapeutic and research tool

"Trastuzumab is a monoclonal antibody targeting HER2-overexpressing breast cancer cells."

"cytokine"

a small secreted protein released by cells that has a specific effect on the interactions and communications between cells, regulating immune responses

"The cytokine storm observed in severe COVID-19 is characterised by dysregulated overproduction of pro-inflammatory mediators."

"interleukin (IL)"

a subgroup of cytokines produced mainly by leukocytes that mediate communication between immune cells

"IL-6 is a pleiotropic interleukin that drives fever, acute-phase protein production, and B cell differentiation."

"tumour necrosis factor (TNF)"

a pro-inflammatory cytokine produced mainly by macrophages that plays a central role in inflammation, apoptosis, and anti-tumour immunity

"Anti-TNF biologics such as adalimumab are first-line treatments for moderate-to-severe rheumatoid arthritis."

"chemokine"

a small cytokine that acts as a chemoattractant to guide the migration of immune cells towards sites of infection or injury

"CXCL8 (IL-8) is a potent chemokine that recruits neutrophils to sites of acute bacterial infection."

"inflammasome"

a multiprotein intracellular complex that detects danger signals and activates caspase-1 to process and release pro-inflammatory cytokines IL-1β and IL-18

"Uric acid crystals in gout activate the NLRP3 inflammasome, driving joint inflammation."

"prostaglandins"

lipid mediators derived from arachidonic acid that contribute to vasodilation, pain sensitisation, and fever during inflammation

"NSAIDs reduce inflammation by inhibiting cyclooxygenase enzymes responsible for prostaglandin synthesis."

"acute-phase response"

a systemic inflammatory response to tissue injury or infection characterised by fever, leukocytosis, and changes in plasma protein concentrations

"C-reactive protein is a widely used acute-phase response marker for monitoring inflammation in clinical practice."

"NF-κB pathway"

a major intracellular signalling pathway that regulates the transcription of genes encoding pro-inflammatory cytokines, adhesion molecules, and survival factors

"Persistent NF-κB pathway activation in tumour cells promotes their survival and resistance to apoptosis."

"autoantibody"

an antibody produced by the immune system that is directed against the host's own proteins or tissues, characteristic of many autoimmune diseases

"Anti-double-stranded DNA autoantibodies are highly specific for systemic lupus erythematosus."

"molecular mimicry"

a mechanism in which structural similarity between a pathogen antigen and a self antigen leads to cross-reactive immune responses that damage host tissue

"Molecular mimicry between streptococcal M protein and cardiac myosin contributes to rheumatic heart disease."

"self-tolerance"

the ability of the immune system to recognise and refrain from attacking the body's own molecules and tissues

"Central and peripheral tolerance mechanisms together ensure self-tolerance in healthy individuals."

"type I hypersensitivity"

an IgE-mediated immediate allergic reaction triggered by allergen cross-linking of IgE on mast cells, causing rapid release of histamine and other mediators

"Anaphylaxis is the most severe manifestation of type I hypersensitivity and requires immediate epinephrine administration."

"mast cell degranulation"

the release of pre-formed inflammatory mediators such as histamine, tryptase, and leukotrienes from mast cell granules upon IgE receptor cross-linking

"Mast cell degranulation in bronchial tissue triggers the bronchospasm characteristic of acute asthma."

"antinuclear antibody (ANA)"

an autoantibody that binds to antigens within the cell nucleus, used as a serological marker for systemic autoimmune diseases

"A positive antinuclear antibody test with a titre above 1:160 is found in more than 95% of lupus patients."

"Th2 response"

an adaptive immune response characterised by IL-4, IL-5, and IL-13 production that drives IgE class switching, eosinophil activation, and allergic inflammation

"Atopic individuals mount exaggerated Th2 responses to common environmental allergens such as house dust mites."

"immune privilege"

a property of certain anatomical sites, such as the eye and brain, where immune responses are actively suppressed to protect delicate tissues from immunopathology

"Breakdown of immune privilege in the central nervous system underlies autoimmune diseases such as multiple sclerosis."

"adjuvant"

a substance added to a vaccine formulation that enhances and modulates the immune response to the co-administered antigen

"Aluminium salts are the most widely used adjuvants in licensed human vaccines worldwide."

"herd immunity"

the indirect protection from infection that occurs when a sufficiently large proportion of a population has become immune, reducing pathogen transmission

"For measles, herd immunity requires approximately 95% of the population to be vaccinated."

"checkpoint inhibitor"

a class of cancer immunotherapy drug that blocks inhibitory receptors on T cells, such as PD-1 or CTLA-4, to reinvigorate anti-tumour immune responses

"Pembrolizumab, a PD-1 checkpoint inhibitor, has transformed the treatment of advanced melanoma."

"CAR T-cell therapy"

a form of adoptive cell therapy in which a patient's T cells are genetically engineered to express a chimeric antigen receptor targeting a tumour antigen

"CD19-targeting CAR T-cell therapy has achieved durable remissions in relapsed B-cell acute lymphoblastic leukaemia."

"immunosuppression"

the reduction of the activation or efficacy of the immune system, achieved with drugs or biological agents to prevent transplant rejection or treat autoimmunity

"Tacrolimus-based immunosuppression regimens are standard of care following solid organ transplantation."

"mRNA vaccine"

a vaccine that delivers messenger RNA encoding a pathogen antigen into host cells, which then produce the antigen to stimulate an immune response

"mRNA vaccine platforms allow rapid redesign to match emerging viral variants without live pathogen handling."

"passive immunisation"

the transfer of preformed antibodies from one individual or source to another to provide immediate but temporary protection against a pathogen

"Palivizumab provides passive immunisation against respiratory syncytial virus in high-risk neonates."

"bispecific antibody"

an engineered antibody that can simultaneously bind two different antigens or epitopes, often used to redirect immune cells towards tumour targets

"Blinatumomab is a bispecific antibody that bridges CD19-positive B-cell tumours with CD3-positive T cells to mediate killing."