Auto-antibodies specific for beta 2 microglobulin in normal human serum

Area of Science:

• Immunology
• Biochemistry

Background:

• Beta 2 microglobulin (beta 2m) is a protein found on the surface of most nucleated cells.
• The presence and function of natural auto-antibodies against beta 2m in healthy individuals are not fully understood.

Purpose of the Study:

• To investigate serum components with binding activity towards free human beta 2 microglobulin (beta 2m) in healthy adults.
• To characterize the nature and affinity of these binding activities.

Main Methods:

• Serum components were treated with dissociating buffers to reveal binding activity.
• Purification techniques including AcA 44 filtration, DEAE chromatography, and immunopurification on beta 2m-Sepharose were employed.
• Pepsin digestion of serum IgG was performed to generate F(ab')2 fragments for specific antibody preparation.

Main Results:

• Binding activity towards beta 2m was enhanced after treatment with dissociating buffers.
• The binding activity was localized to the serum IgG fraction.
• Specific anti-beta 2m F(ab')2 fragments retained the beta 2m binding capacity.
• Saturation analysis indicated high affinity constants (K values between 1.5 and 9.5 X 10(9) L/M).

Conclusions:

• Normal human serum contains minute amounts of auto-antibodies specific for beta 2m.
• These auto-antibodies exhibit relatively high affinities for beta 2m.