An RT6a gene is transcribed and translated in lymphopenic diabetes-prone BB rats.
T-cells expressing the RT6 surface alloantigen appear to perform important immunoregulatory functions in the rat. Diabetes-prone BB rats lack circulating RT6+ T-cells and spontaneously develop autoimmune diabetes mellitus and thyroiditis. The coisogenic diabetes-resistant BB rat does circulate RT6+ T-cells and is free of disease. Transfusions leading to engraftment of RT6+ T-cells prevent both diabetes and thyroiditis in the diabetes-prone rat. To investigate the absence of this subset in the lymphopenic BB rat, we used both molecular and biochemical procedures and made the following observations: 1) an mRNA encoding RT6 protein is present in diabetes-prone spleen cells; 2) nucleotide sequencing of this transcript reveals an intact coding sequence for the RT6.1 alloantigen; 3) sensitive chemiluminescent assay of diabetes-prone lymph node cell detergent extracts shows that diabetes-prone RT6 mRNA is translated in vivo; 4) quantitatively, diabetes-prone lymph node cells express < or = 10% of the RT6.1 protein found on similar numbers of diabetes-resistant BB cells; and 5) finally, we obtained evidence of an intact phosphatidylinositol linkage of the molecule to the cell surface and successfully immunoprecipitated the phosphatidylinositol-linked protein with DS4.23 monoclonal antibody, indicating that the RT6.1 antigen is correctly processed and folded in diabetes-prone lymph node cells. We conclude that the near total absence of RT6+ T-cells in the diabetes-prone BB rat is unlikely to be because of a defect in RT6 gene expression per se. Defects in RT6 gene regulation or other cellular defects leading to premature cell death in the T-cell lineage, alone or in combination, may instead be responsible.
Crisá
L
L
Diabetes Division, University of Massachusetts, Worcester Medical Center 01605.
Sarkar
P
P
Waite
D J
DJ
Friedrich
F H
FH
Koch-Nolte
Rajan
T V
TV
Mordes
J P
JP
Handler
E S
ES
Thiele
H G
HG
Rossini
A A
AA
D036002:ADP Ribose Transferases; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D001921:Brain / Q000276:immunology; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics* / Q000276:immunology; D006649:Histocompatibility Antigens / Q000235:genetics*; D008099:Liver / Q000276:immunology; D008562:Membrane Glycoproteins; D009928:Organ Specificity; D016133:Polymerase Chain Reaction / Q000379:methods; D014176:Protein Biosynthesis; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D011913:Rats, Inbred BB / Q000235:genetics*; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014158:Transcription, Genetic
D000945:Antigens, Differentiation, T-Lymphocyte; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D012313:RNA; D036002:ADP Ribose Transferases; C090163:Art2b protein, rat