Antibodies. Properties and functions of the immunoglobulins

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Antibodies. Properties and functions of the
immunoglobulins
Vinnitsa National Pirogov Memorial Medical
University / Department of microbiology
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Antibody

• Antibodies or immunoglobulins (Ig) are a group of
  glycoproteins present in the blood serum and
  tissue serum

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Functions of immunoglobulins

1. Complement activation
2. Opsonization
3. Prevention of microorganism attachment
4. Neutralization toxins and viruses
5. Restriction of microorganism mobility
6. Agglutination of bacteria

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Immunoglobulin structure
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Classes of immunoglobulins

• Ig G ? (gamma)
• Ig A a (alpha)
• Ig M µ (mu) H-chain
• Ig D d (delta)
• Ig E e (epsilon)
• L chains ? (kappa) or ? (lambda)

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Structure of the immunoglobulin monomer molecule
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Immunoglobulin antigen determinants

• Isotypic markers
• Allotypic markers
• Idiotypic markers

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Immunoglobulin classes

• Ig G.
• It has molecular weight 160 000 D
• The normal serum concentration of Ig G is 8-16
  mg/ml.

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Ig A

• It constitutes 10-15 of total serum globulin
• Normal serum level is 0,6-4,2 mg/l
• It has molecular weight 170 000 D

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Differences between serum and secretory Ig A
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Ig M

• It constitutes 5-10 serum globulin or 0,5-2
  mg/ml
• It has half-life of 5-10 days and molecular
  weight 900 000 D

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Ig D

• its concentration in average is 0,02-0,2 mg/ml)
• It has half-life of 3 days and molecular weight
  160 000 D

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Ig E

• It makes up only 0,0002-0,002 of the total
  immunoglobulin pool
• It has half-life of 2 days and molecular weight
  190 000 D

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The types of antibody response to antigen
stimulation

• Immune antibody response consists of 3 steps
• Entry and distribution of Ag in tissue and its
  contact with immunological competent cells
• Processing of Ag and control of Ab forming
  process
• Secretion of Ab, its distribution in tissue, body
  fluid and manifestation of its effect

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• Primary immune response
• It is slow
• Specific IgM can be detected in the serum from
  the 4th day, titer rises to 7-12 days
• Specific IgG can be detected in the serum from
  the 7th day and titer rises to 10-14th days

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• Secondary antibody response
• shorter lag phase
• IgM and IgG are synthesized in the same time
• It is provided by IgG

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The types of the antibody immune response
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