Serological reactions

1. Serological reactions • Reaction of antigen and antibody in laboratory conditions in different (stated) environment • Antigen – substance with ability to activise immune system to specific antibodies production. Non self substance. Immunogenicity. Protective antibodies • Antigenic determinants – areas of microorganism with a structure eliciting the antibodies production • Specificity of antigen – determined by production of antibodies, that reacts only with it. Non specific antigens – heterofil – if antibodies agains them react with other antigens

2. Antibodies • In blood serum of immunised annimals there are specific proteins – immuneglobulins, that bind antigens causing their production (behring, Kitaso, 19 th century) • Serum – liquid that will remain at the top of the tube after centrifugation of coagulated blood • Plasma – liquid that remains at the toop of tube after centrifugation of not coagulated blood • Antiserum – serum with specific antibodies • Function of antibodies – to bind specifically antigen, neutralise its function via other reactions that are activised by the antigen antibody binding (complement activation....)

3. Serological reaction • Reaction of antigen with specific antibody depends on the type of antigen – formes immunocomplexes of different quality *corpuscular antigens –(microorganism, erytrocytes) = agglutination *soluble antigens – small imunocomplexes – in solution or precipitation

4. Electrophoresis of proteins • Alfa, beta, gama fraction • Immunoglobulines – 5 classes IgG, IgA, IgM, IgD, IgE - types of heavy chains: mi, delta, gama, alfa, epsilon • – subclasses IgG1, IgG2, IgG3, IgG4,, • types of light chains – kappa, lambda, subtypes : lambda 1,2,3,4,

5. Antibodies production - dynamics • Acute antibodies IgM • Persistent antibodies IgG - protective • First response IgM • Booster effect second response • Total antibodies

6. Serological reactions • Agglutination – antigen + several dilution of serum = visible agglutination • Latex agglutination – antibody bound on latex particles + Ag = big agglutination • Precipitation – Ag+Ab = ring in the touch zone • Immunediffusion – diffusion of Ag and Ab in agar. In the meeting point – precipitation ring • Neutralisation – serum with antibodies can neutralise the activity of microorganisme in living model • Hemagglutination – passive agglutination – ag is bound on the surface of RBC • CF – complement fixation- Ag +Ab +C´+ Ery + antieryab –lysis • ELISA, RIA, IFT

7. Reading of serological reactions • Qualitative reaction – positive or negative (comparison with bordeline value) • Quantitative reaction – titer of antibodies, or concentration Determination of total antibodies (CF,) – dynamics of antibody production – 2 samples in the interval of 14-21 days. Results – titer of antibodies = 1:16(dilution )., 16(Titer – amount of antibodies in not diluted serum) Determination of immuneglobulin classes – IgA, igM – acute IgG – long lasting, protective, Results – in concentration of antibodies – g/l Confirmation of acute infection: Seroconversion – from negativity to positivity, fourfold increase of total antibody titer, or presence of IgM