VMC 221: Veterinary Immunology and Serology (1+1)

EHRLICH'S SIDE CHAIN THEORY (SELECTIVE THEORY)

• Paul Ehrlich (1900) proposed this theory.
• Cells were considered to have surface receptors, which can bind with complementary ‘side chains’.
• These receptors are used for absorption of nutrients.
• When foreign substance or antigen enters into the body, they combine with the complementary surface receptor and inactivate them.

B cell contains different side chains (antibodies) with different specificity

 

• As a compensatory mechanism, there is over production of the same type of receptors and large numbers of them are liberated into the blood as circulatory antibodies.
• But this theory was abandoned when Land Steiner demonstrated that antibodies are also produced against various synthetic chemicals besides natural antigens.