BIO 343 Lecture Notes - Lecture 18: Antigen, Titer, Immunoglobulin G
Immunology Techniques
Hayden Casassa
• Enzyme-Linked Immunosorbent Assay (ELISA)
o Detects and quantitates amount of antigen, antibody present in sample
o Very sensitive and specific
• What can be detected and quantified in an ELISA
o Miroial atiges i patiet’s seru
o Antibodies specific for given pathogen
o Total level of abs or cytokines
• Indirect ELISA
o Measures amount of antibody specific for given antigen present in sample
• Sandwich ELISA
o Measures amount of antigen present in sample
o This antigen could be cytokine, or even amount of total antibody (IgG)
• Quantifying ELISA results using standard curve
o Set up similar to BCA curve in that you have set of concentration standards
• Agglutination
o Cross-linking that occurs between specific antibodies and an insoluble particulate antigen that
results in visible clumping of the complexes
o Different than precipitation as Agglutination uses insoluble vs soluble in precipitation
• Agglutination Reactions
o Antibody + Insoluble Ag → Visible clumping
o Assays detect presence of either Antigen or Abs specific for antigen
• Hemagglutination reactions are used for RBC typing
o If an Anti-A Ab is used and clumping occurs then it is likely A and if Anti-D lups the it’s A+
• Bacterial Agglutination
o Detects presence of antibody specific for a given bacteria in a particular patient sample
o Question posed is does patient have antibodies against certain type of bacteria?
▪ If yes, then clumping or previous/ active infection
• Bacterial Agglutination and Titers
o Detects specific antibody
o Add same number of bacteria to serial dilution of serum
o Agglutination titer→ reciprocal of highest dilution that gives positive agglutination
o Collect serum early and later as rising titer means active infection
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