--- module: 094-03 language: en chapter: 94 title: "Immune Development, Tolerance, Hypersensitivity, and Immunological Methods" module_title: "Vaccines, immunological assays, monoclonal therapies, and immune manipulation" source_sha256: 6a331c5de59ba3feb4580142ac4216735667ec1274bfd12380f842bfab7669e6 --- # Vaccines, assays, and immune therapies ## Vaccine platforms ### Live attenuated: limited replication #### Strong humoral, cellular, mucosal memory #### Risk in severe immunodeficiency or pregnancy ### Inactivated whole organism cannot replicate #### Needs adjuvant and repeated doses ### Subunit and recombinant: safer, narrower epitopes ### Toxoid: antibodies against inactivated toxin ### Polysaccharide: T-independent, weak in young children #### Conjugation recruits helper T cells #### Class switching, memory, reduced carriage ### Viral vectors: class I and II presentation #### Vector immunity can reduce boosting ### mRNA in lipid particles, DNA as plasmid ## Shaping and judging vaccine responses ### Adjuvants activate innate sensors #### Aluminium salts favour antibody ### Reactogenicity is not protection ### Booster recruits memory, faster, higher affinity ### Longer intervals: maturation versus vulnerability ### Correlate versus mechanistic correlate of protection #### Waning antibody is not lost protection ### Sterilising versus disease-modifying immunity ### Herd protection not a fixed percentage ## Binding and imaging assays ### ELISA: indirect, sandwich, competitive #### Binding does not prove neutralisation #### Cut-offs trade sensitivity and specificity ### Immunoblot gives size plus binding ### Immunofluorescence localises antibody or antigen ### Immunohistochemistry depends on fixation and controls ### Agglutination visualises antigen-antibody lattice #### Prozone: antibody excess, false negative #### Dilution corrects prozone ### Nephelometry measures light scattering ## Cellular assays ### Flow cytometry measures single cells #### Gating, compensation, controls set boundaries #### Absolute counts need beads or blood count #### Marker presence is not function ### Intracellular staining after permeabilisation ### Tetramers find peptide-MHC-specific T cells ### Functional assays: neutralisation, killing, burst #### Neutralisation methods not interchangeable ## Complement and autoantibody testing ### Low classical, normal alternative: early classical ### Both low: C3, terminal deficiency, consumption ### Low alternative only: alternative defect ### Handling can activate complement in vitro ### Cell-based assays preserve membrane conformation ### Low positives without phenotype mislead ## Antibody and cellular therapies ### Monoclonals neutralise, block, deplete, deliver #### Fc region controls half-life and effector use #### Human sequence still allows anti-drug antibodies ### Anti-TNF raises tuberculosis risk ### B-cell depletion spares long-lived plasma cells ### Complement inhibitors: encapsulated bacteria risk ### Checkpoint inhibitors release peripheral restraint #### Immune adverse events in nearly any organ #### May appear after therapy stops ### CAR T cells recognise antigen without MHC #### Cytokine release, neurotoxicity, antigen escape ## Immunosuppression and tolerance induction ### Glucocorticoids: transcription and trafficking ### Calcineurin inhibitors block cytokine transcription ### mTOR inhibitors restrain growth ### Combination compounds infection and toxicity ### Desensitisation lasts only with exposure ### Allergen immunotherapy seeks lasting deviation ## Interpreting immune measurements ### Pretest probability comes first ### Predictive values depend on prevalence ### Drug monitoring: trough, anti-drug antibodies #### Targets not transferable between settings ### Measurements are imperfect proxies ### Conclusions need syndrome, method, controls