Agglutination Aggregation of insoluble or particulate antigens with antibody to form visible complex How does this differ from precipitation? –Antigens are soluble with precipitation

Types of Agglutination Agglutination Direct or Active –Antigens found naturally on cell surface Indirect, Passive or Inactive –Known antigen is attached to a particulate “carrier,” looking for unknown antibody Reverse passive or Reverse inactive –Known antibody is attached to a particulate “carrier,” looking for unknown antigen

Types of Agglutination Agglutination Anti-A This indicates that the RBCs ________________________________. Clumping of RBCs are positive for the “A” antigen

Types of Agglutination Agglutination Latex bead suspension coated with Group A Streptococcus This is an example of_______________. passive agglutination Patient Serum Clumping in latex suspension

Types of Agglutination Agglutination Latex bead suspension coated with Grp A Streptoccoccus The serum contains _________________. antibodies to Grp A Strep Patient Serum Clumping in latex suspension

Agglutination Inhibition Agglutination

Neutralization If patient serum has antibody to DNase B, then enzyme is neutralized and not allowed to break down DNA. DNA & indicator DNase B (breaks down DNA) Enzyme break down of DNA is indicated by indicator change Antibody neutralizes effects of a substrate

DNase B Patient’s serum incubate DNase B & patient serum DNA & indicator What does the result mean? Patient serum is positive for the DNase B antibody since the DNase B enzyme was neutralized. Neutralization

DNase B Patient’s serum incubate DNase B & patient serum DNA & indicator What does the result mean? Patient serum is negative for the DNase B antibody since the DNase B enzyme was not neutralized.

Complement Fixation Detects antigen-antibody complexes with indicator system of complement (usually guinea pig) and hemolysin-sensitized RBCs –(sensitized RBCs = RBC coated with complement-fixing Ab) Complement will bind to Ag-Ab complexes Complement fixed to sensitized RBC will lyse the RBC

Complement Fixation Test

Known antigen Patient serum Complement (guinea pig) Incubate Hemolysin (RBCs coated with antibody) Incubate No hemolysis of RBCs ∴ complement fixed in first incubation ∴ patient positive for antibody Results:

Complement Fixation Test Pos Control Neg Control Patient Patient negative for antibody, C not fixed in 1 st step & available to lyse sensitized RBCs Known antigen Patient serum Complement (guinea pig) Incubate Hemolysin (RBCs coated with antibody) Incubate Results: