Immunology

The study of the immune system, including recognition, regulation, protection and pathological responses. A strong measured response need not equal better protection if the same activity damages host tissue.

Nutritional immunity is a host-defense strategy that limits the supply of nutrients available to a pathogen. Restricting access to needed metal ions is one example: a host protein can bind a metal so that its presence in tissue does not imply that invading bacteria can acquire it.

A concrete experimental example is calprotectin in Staphylococcus aureus abscesses. Brian D. Corbin and colleagues found that neutrophil-derived calprotectin inhibited bacterial growth through chelation of manganese and zinc. Abscesses in mice lacking calprotectin contained more metal and supported greater bacterial proliferation. The combination of growth inhibition and the comparison with deficient animals connects metal sequestration to a host defense, rather than merely showing that a binding protein is present at an infection site.^[ref]

A simple two-pool model makes the distinction between total amount and accessibility explicit. Write the total metal concentration as $M_T=M_{\mathrm{free}}+M_{\mathrm{bound}}$. If $M_T=1\mu \mathrm{mol}{\mathrm{L}}^{-1}$ and $99\%$ is bound, the free concentration is only $0.01\mu \mathrm{mol}{\mathrm{L}}^{-1}$: one hundredth of the value if all the metal were free. These are illustrative numbers, not measurements from the experiment. Actual microbial access also depends on whether a bacterium can obtain metal from the bound pool; total metal concentration alone therefore does not measure nutrient availability.

Interacting cells, molecules and tissues that recognize and respond to threats or altered biological material. Its responses include both defense and regulation, rather than unrestricted elimination of every foreign molecule.

A preparation intended to induce protective immune memory or another useful immune response against a target. The induced response is a mechanism; reduction of infection, severe disease or another outcome requires appropriate evidence.

Administration of a vaccine to induce a useful immune response. Receipt of a dose, development of measurable antibodies and protection from disease are distinct endpoints, so vaccination status does not directly measure every part of immunity.

A person's reported intention or willingness to receive a vaccine under the conditions of a question. It is distinct from actual vaccination status. The response depends on the question, time and circumstances; an intention score does not directly measure later receipt or a medical effect.

A record of which vaccinations a person has received at a specified time. A binary categorical variable may collapse this into two recorded categories; the categories alone do not specify number of doses, timing, protective immunity or willingness to receive a vaccine.

A host with sufficiently functional immune defenses for the specified comparison. Competence is contextual rather than a guarantee of resistance to every infection or an absence of immune variation.

Cellular and molecular changes following recognition of a challenge. Increased activation can reflect increased exposure or damage, so its magnitude is not interchangeable with protective capacity.

Immune defense using pre-existing recognition and response mechanisms, including barriers and rapid cellular reactions. It is distinguished from antigen-specific adaptive responses without implying that its behavior is identical in every prior exposure state.

Immune responses involving antigen-specific lymphocyte recognition and the capacity for memory. Expansion of selected cell populations connects molecular specificity with a changed response on later exposure.

A coordinated tissue response involving immune activity, vascular changes and cellular signaling after injury or challenge. It can support defense and repair while also causing damage when excessive or persistent.

Inflammation of the spinal cord. Its effects depend on the affected pathways and level, distinguishing an anatomical syndrome from one unique infectious or immune cause.

Inflammation of the pleura.

Inflammation of the synovial lining of an anatomical joint. It can cause swelling and contribute to tissue injury through infectious, autoimmune or other mechanisms.

A localized collection of pus.

A localized collection of pus in the retropharyngeal space. Its deep neck location can affect swallowing or the airway, distinguishing it from a superficial throat lesion.

A collection of pus in tissues around a tonsil. The localized cavity differs from uncomplicated diffuse tonsillitis, despite overlapping pain and inflammation.

An organized aggregate of immune cells, commonly including activated macrophages. It is a pattern of tissue response with infectious and noninfectious causes, not a synonym for tuberculosis.

Fluid and associated material leaving the blood circulation because of altered vascular permeability, typically during inflammation. Its composition differs from fluid accumulating mainly through pressure or protein-balance changes.

Material that leaves the blood vessels during inflammation. Historical theories of its formation and removal should be distinguished from current pathology.

An inflammatory exudate rich in fibrin.

Experimental manipulation intended to stimulate an immune response. A nonreplicating inflammatory stimulus separates some host responses from effects of a live pathogen, but need not reproduce natural infection.

Reduction of health or fitness damage for a given pathogen burden. Low symptoms alone cannot distinguish tolerance from successful disease resistance.

Reduction of pathogen burden through prevention or control of infection. It differs from disease tolerance, which reduces damage at a given burden.

Study of interactions among animal behaviour, the nervous system and immunity. Bidirectional mechanisms require interventions or temporal evidence beyond a cross-sectional association.

Collective protection against pathogens arising through interactions among individuals, including hygienic behaviour. A colony-level reduction in infection need not be increased cellular immunity in every worker.

An antigen-presentation system displaying peptides to appropriate CD4 T cells. Its usual source and processing route differ from the intracellular-protein sampling pathway of MHC class I.

A major histocompatibility complex presentation system displaying intracellularly derived peptides to appropriate T cells. Presentation and direct CAR recognition have different requirements.

An altered T-cell functional and regulatory state associated with persistent stimulation. Blocking one inhibitory receptor need not reverse every component of the state.

Human leukocyte antigen, the human MHC system. Particular HLA molecules restrict which peptides a conventional T-cell receptor can recognise.

An intervention intended to generate or strengthen immune recognition of tumour-associated targets. Successful priming does not guarantee entry or function within a tumour.

Transfer of prepared T cells to a patient to supply or amplify a therapeutic immune response, including expanded tumour-derived or genetically engineered populations.

Treatment that interferes with inhibitory immune regulatory interactions, such as PD-1/PD-L1 or CTLA-4-associated restraint. It requires a usable antitumour recognition and effector system.

Display of antigen-derived material for immune recognition, including peptide display by MHC molecules to T-cell receptors. Processing, expression and recognition are distinct requirements.

Presentation of externally acquired antigen on MHC class I. Dendritic cells can thereby prime antiviral CD8 responses without themselves being productively infected.

Dependence of a T-cell response on both a recognized peptide and a compatible presenting MHC molecule. Infected matched and mismatched targets distinguish it from recognition of viral infection alone.

A component of the MHC-class-I peptide-loading machinery. It helps connect peptide supply and selection to stable class-I display.

Transporter associated with antigen processing, supplying peptides to the endoplasmic reticulum for MHC-class-I loading. Peptide-pulsing experiments can bypass this transport step.

A scientist or clinician studying the immune system and its disorders. An immunologist connects molecular recognition and cellular responses with protection, regulation or immune-mediated injury.

Tim R. Mosmann is an immunology researcher whose work includes quantitative cellular assays and analysis of T cell responses. His Rochester laboratory identifies him by this name and directly lists the 1983 colorimetric-assay paper published as T. Mosmann. This provides an institutional link between the initial-only byline and the named researcher; the R. is retained without expansion.^[ref]

In 1983, Tim R. Mosmann reported a tetrazolium salt-based colorimetric method for mammalian cell survival, cell proliferation and activation. The paper's abstract describes a multiwell scanning spectrophotometer readout and explicitly notes that signal depends on activation. The experimental contribution therefore includes both a convenient quantitative assay and a qualification on its biological interpretation.^[ref]

An original measurement model illustrates that qualification. Suppose a background-corrected signal is $S=kNm$, where $N$ is the number of contributing cells, $m$ their mean per-cell reducing activity under the assay conditions and $k$ an instrumental factor. Doubling $N$ at unchanged $m$ doubles the signal, but doubling $m$ at unchanged $N$ does too. The single scalar signal does not identify both quantities.

For stipulated initial $N=100$ and $m=1$, the products $Nm$ for later populations $(N,m)=(200,1)$ and $(100,2)$ are both 200. A larger readout alone cannot distinguish proliferation from increased activity per cell. Conversely, halving cell number while doubling mean activity can leave the total unchanged. These are model examples, not data from the 1983 paper.

Controls with known cell numbers, appropriate blanks and independent biological observations help establish which interpretation applies. The general lesson is to connect cell viability and cell proliferation claims to a validated response model, rather than assigning every absorbance change to one mechanism.

The laboratory also describes computational analysis of high-dimensional flow cytometry measurements of T cells.^[ref] That scientific setting likewise requires distinguishing a measured signal pattern from the underlying populations it is intended to represent.

E. A. Carswell is the first-listed author of a 1975 paper describing a host-derived serum activity named tumor necrosis factor. The researchers investigated necrosis in transplanted tumors and distinguished the serum factor's activity from that of residual endotoxin. This supported an indirect route in which a host response could mediate an effect initially associated with the stimulating material.^[ref]

The paper also compared responses in cultured cells: the tested neoplastic cell lines and mouse embryo cultures differed in susceptibility. This is an illuminating experimental distinction between observing a biological effect and identifying its range. It did not establish that every tumor responds, that every other cell is unaffected, or that a therapeutic application follows automatically. A macrophage origin was proposed as an interpretation, rather than directly identified by these experiments.^[ref]

Researcher connecting immunology and nervous-system function. Filiano and collaborators investigated a role for interferon-gamma in neuronal connectivity and social behavior, testing how an immune signal can affect interactions among neurons.^[ref]

Researcher in immune-cell migration. Lämmermann and collaborators investigated rapid leukocyte movement through flowing and squeezing without obligatory integrin adhesion, connecting cell mechanics with movement through confined tissue.^[ref]

Immunologist whose work investigated antibody structure and its relationship to molecular recognition. His Nobel lecture connects chemical analysis of immunoglobulins with an explanation of how antibody chains and domains support biological specificity.^[ref]