Human autologous mixed lymphocyte reaction as an in vitro model for autoreactivity to apoptotic antigens.
Recent studies have indicated that cells undergoing apoptosis are the source of autoantigens which drive autoimmune responses in systemic lupus erythematosus (SLE). It has been recognized for many years that in vitro stimulation of T cells with irradiated major histocompatibility complex (MHC) class II-bearing autologous cells results in T-cell proliferation with immunological specificity and memory, namely the autologous mixed lymphocyte reaction (AMLR). The nature of the major stimulants in the AMLR is still unclear. We investigated whether apoptotic fragments from irradiated cells act as antigenic stimulators for AMLR or nucleohistone-primed T cells. T-cell proliferation in the primary AMLR was significantly suppressed by the presence of a caspase inhibitor Z-Val-Ala-Asp-CH2F (Z-VAD.fmk), indicating that apoptotic antigens released from irradiated autologous feeder cells act as stimulators of AMLR T cells. This inhibitory effect of Z-VAD was not caused by toxic effects, because the T-cell response to the mitogen phytohaemagglutinin (PHA) was not inhibited by Z-VAD. A nucleohistone preparation was shown to contain antigens that are important in the AMLR, as culture with nucleohistone (but not with thyroglobulin or hen-egg lysozyme) primed T cells to respond with secondary kinetics in a subsequent AMLR that was also suppressed by Z-VAD. Our data provide evidence that the AMLR constitutes a model for the evaluation of cellular and molecular mechanisms that may be relevant to the pathogenesis of SLE and similar autoimmune diseases.
Amel Kashipaz
Mohammad R
MR
Division of Molecular and Clinical Immunology, School of Clinical Laboratory Sciences, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK.
Huggins
Mary L
ML
Powell
Richard J
RJ
Todd
Ian
I
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000276:immunology* / Q000528:radiation effects; D001324:Autoantigens / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology*; D015551:Autoimmunity; D061945:Caspase Inhibitors; D002455:Cell Division / Q000187:drug effects; D018920:Coculture Techniques; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005720:Gamma Rays; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008213:Lymphocyte Activation; D007959:Lymphocyte Culture Test, Mixed; D018448:Models, Immunological; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
D000590:Amino Acid Chloromethyl Ketones; D001324:Autoantigens; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone