Analysis in deoxycholate of three antigenic specificities associated with the rat Thy-1 molecule

Area of Science:

• Immunology
• Molecular Biology
• Cell Surface Antigens

Background:

• Rat thymocytes express three antigens with similar tissue distribution: Thy-1.1, a rat-specific xenoantigen, and a rat-mouse cross-reacting xenoantigen.
• Understanding the molecular identity of these antigens is crucial for characterizing thymocyte populations and immune responses.

Purpose of the Study:

• To determine if the three identified antigens on rat thymocytes are located on the same molecular entity.
• To investigate the molecular behavior of these antigens in detergent-solubilized extracts.

Main Methods:

• Preparation of membrane fragments from rat thymocytes using Tween-40 detergent.
• Solubilization of antigens using deoxycholate and subsequent ultracentrifugation.
• Chromatography on Sephadex G-200 and zone sedimentation on sucrose gradients to analyze hydrodynamic properties.
• Immunoabsorption using antibodies against xenoantigens to assess antigen association.

Main Results:

• Detergent-solubilized extracts retained significant Thy-1.1 and xenoantigen activity.
• All three antigens exhibited identical migration patterns during chromatography and sedimentation, behaving as a single molecule of approximately 28,000 daltons.
• Immunoabsorption experiments demonstrated co-depletion of all three antigens, indicating close association.

Conclusions:

• The Thy-1.1 antigen and the two studied xenoantigens are closely associated on rat thymocytes.
• Evidence strongly suggests that these three antigens are located on the same Thy-1 molecule.