High frequency apoptosis of recent thymic emigrants in the liver of lymphopenic diabetes-prone BioBreeding rats

J Immunol. 1998 Jun 15;160(12):5838-50.


Diabetes-prone (DP) BioBreeding (BB) rats develop spontaneous autoimmune diabetes. DP-BB thymocyte export is reduced, and most thymic emigrants disappear rapidly from peripheral lymphoid tissues. DP-BB rats are consequently lymphopenic and circulate severely reduced numbers of T cells. Peripheral T cells present are phenotypically immature (Thy1+) and appear activated. We hypothesized that DP-BB recent thymic emigrants have a shortened life span and disappear by apoptosis. The percentage of T cells with an alphabetaTCR(low) B220+ CD4- CD8- phenotype was increased in DP peripheral lymphoid tissues when compared with normal, nonlymphopenic diabetes-resistant (DR) BB rat tissues. There was no evidence of DNA fragmentation in freshly isolated DP- or DR-BB rat cells, but, after 24 h of culture, a higher proportion of DP- than DR-BB splenic T cells underwent apoptosis. We then tested the hypothesis that BB rat T cells with the alphabetaTCR(low) B220+ CD4- CD8- phenotype accumulate and undergo apoptosis in the liver. Such cells were observed undergoing apoptosis in both DP- and DR-BB rats, but comprised approximately 80% of intrahepatic T cells in DP vs approximately 20% in DR-BB rats. Most alphabetaTCR(low) B220+ CD4- CD8- cells in the liver were also Thy1+. The data suggest that T cell apoptosis in the DP-BB rat is underway in peripheral lymphoid tissues and is completed in the liver. Increased intrahepatic apoptosis of recent thymic emigrants appears in part responsible for lymphopenia in DP-BB rats and the concomitant predisposition of these animals to autoimmunity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis*
  • Diabetes Mellitus, Type 1 / complications
  • Diabetes Mellitus, Type 1 / immunology
  • Diabetes Mellitus, Type 1 / physiopathology*
  • Female
  • Liver / immunology
  • Liver / physiopathology*
  • Lymphopenia / complications
  • Lymphopenia / immunology
  • Lymphopenia / physiopathology*
  • Male
  • Rats
  • Rats, Inbred BB
  • Receptors, Antigen, T-Cell / immunology
  • T-Lymphocytes / immunology
  • T-Lymphocytes / physiology*


  • Receptors, Antigen, T-Cell