A 10-year-old child had cut his leg with a glass shard, when playing, and was delivered to the outpatient department to receive antitetanus serum. To prevent development of anaphylactic shock the serum was introduced by Bezredka method. This method of organism hyposensitization is based on the following mechanism:

Answer options

1. Stimulation of immune tolerance to antigen
2. Binding of mast cell-fixed IgE
3. Stabilization of mast cell membranes
4. Blocking of mast cell mediators synthesis
5. Stimulation of antigen-specific IgG2

Explanation

In the immunologic mechanism of anaphylactic shock, immunoglobulin E (IgE) binds to the antigen (the foreign material that provokes the allergic reaction). Bezredki method – the method of desensitization, necessarily used to prevent anaphylactic reactions.The table below summarizes the characteristics of the five types of immunoglobulin found in the body:TYPEFREQUENCYSHAPENOTESIgG75%Monomer• Enhance phagocytosis of bacteria and viruses • Fixes complement and passes to the fetal circulation • Most abundant isotype in blood serumIgA15%Monomer/ dimer• IgA is the predominant immunoglobulin found in breast milk. It is also found in the secretions of digestive, respiratory and urogenital tracts, and systems • Provides localized protection on mucous membranes • Most produced immunoglobulin in the body (but blood serum concentrations lower than IgG .) • Transported across the interior of the cell via transcytosisIgM10%Pentamer• First immunoglobulins to be secreted in response to an infection • Fixes complement but does not pass to the fetal circulation • Anti-A, B blood antibodies (note how they cannot pass to the fetal circulation, which could of course result in haemolysis) Pentamer when secretedIgD1%Monomer• Role in an immune system largely unknown • Involved in activation of B cellsIgE0.1%Monomer• Mediates type 1 hypersensitivity reactions • Binds to Fc receptors found on the surface of mast cells and basophils • Provides immunity to parasites such as helminths • Least abundant isotype in blood serum