Characterization of two molecules at 30,33 kDa as major target antigens of natural thymocytotoxic autoantibodies.
We have attempted to characterize, by immunoblotting, the cell surface determinants which are recognized by natural thymocytotoxic autoantibodies (NTA). NTA-positive sera from spontaneously autoimmune mice and from mice rendered autoreactive by neonatal induction of tolerance were used as probes on blots of thymocytes. Fifty percent of the sera screened under these conditions reacted with a doublet of 30,33 kDa molecular weight present on membranes, but not detectable on blots of total cell extracts. Additional bands of various molecular weights were detected by NTA-positive sera at a much lower frequency than the 30,33 kDa determinants. Direct evidence of identity between the antibodies inducing thymocytotoxicity and those detecting the doublet in immunoblotting was provided by immunoadsorption tests. Among a panel of immunoadsorbents prepared with thymocyte membrane proteins of various molecular weights, only the one containing the 30,33 kDa molecules efficiently adsorbed cytotoxic antibodies whereas the other preparations containing some of the bands occasionally detected in immunoblotting had practically no effect. In addition we showed that the 30,33 kDa doublet is also detected on membrane preparations of T and B lymphocytes but not on preparations of a nonlymphoid cell line, and is composed of two independent molecules not covalently linked, in their native configuration, by disulfide bonds. Altogether these results strongly suggest that the 30,33 kDa molecules represent major cell surface determinants for thymocytotoxic autoantibodies.
Lehuen
A
A
INSERM U 25, Hôpital Necker, Paris, France.
Carnaud
C
C
D000818:Animals; D000954:Antigens, Surface / Q000302:isolation & purification; D000961:Antilymphocyte Serum / Q000276:immunology* / Q000502:physiology; D001323:Autoantibodies / Q000276:immunology* / Q000502:physiology; D001324:Autoantigens / Q000276:immunology / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007106:Immune Sera / Q000032:analysis; D007163:Immunosorbent Techniques; D008565:Membrane Proteins / Q000302:isolation & purification; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008814:Mice, Inbred NZB; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism
D000954:Antigens, Surface; D000961:Antilymphocyte Serum; D001323:Autoantibodies; D001324:Autoantigens; D007106:Immune Sera; D008565:Membrane Proteins