Immunology and Immunotechnology
Immunology and Immunotechnology tests innate and adaptive immunity, antibody structure, antigen recognition, and diagnostic applications.
Core rules
- Innate immunity is rapid and nonspecific; adaptive immunity is slower, antigen-specific, and retains memory.
- B cells produce antibodies; helper T cells recognize antigen presented on MHC class II; cytotoxic T cells recognize MHC class I on infected cells.
- Antibody structure: two heavy and two light chains, variable regions for antigen binding, constant regions for effector function.
- Polyclonal antibodies bind multiple epitopes; monoclonal antibodies come from a single clone and bind one epitope.
- ELISA, Western blotting, immunofluorescence, and flow cytometry differ in what they measure and how they separate analytes.
- Vaccines may use live attenuated, inactivated, subunit, toxoid, or mRNA platforms.
Worked example
A sandwich ELISA quantifies a serum antigen. A capture antibody is adsorbed to the plate; sample antigen binds; a detection antibody binds a different epitope; an enzyme-labeled secondary antibody converts substrate to a colored product. A standard curve converts absorbance to concentration. A high signal in the negative control suggests nonspecific binding or inadequate blocking, so the run is invalid.
Traps
Do not confuse primary and secondary antibodies. Do not use ELISA to infer molecular weight; Western blotting does that. Do not assume monoclonal is always better; it can be too specific for a polymorphic target. Do not ignore cross-reactivity and hook effects at high antigen concentrations.