Drappa J, Brot N, Elkon KB. The Fas protein is expressed at high levels on CD4+CD8+ thymocytes and activated mature lymphocytes in normal mice but not in the lupus-prone strain, MRL lpr/lpr.
Proc Natl Acad Sci U S A 1993;
90:10340-4. [PMID:
7694292 PMCID:
PMC47770 DOI:
10.1073/pnas.90.21.10340]
[Citation(s) in RCA: 169] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The lymphoproliferation (lpr) mutation in the MRL strain of mice is caused by the insertion of the early transposable element ETn in the Fas gene. The insertion causes a striking decrease in Fas mRNA expression and is associated clinically with marked acceleration of the lupus-like disease. To further explore the role of the Fas protein in T-cell selection in the thymus and tolerance in the peripheral immune system, we produced a monospecific polyclonal anti-murine Fas antibody that binds to a polymorphic region of the protein. Fas protein expression was detected on approximately 90% of BALB/c and MRL +/+ thymocytes, and the expression was highest on CD4+CD8+ thymocytes, the stage at which most thymocytes die by apoptosis. In contrast to the high level of expression of Fas on thymocytes, Fas was detected on < 10% of normal splenic T cells. After activation of splenic T cells with Con A or anti-CD3 and interleukin 2, Fas expression increased approximately 10-fold. Fas expression on splenic B cells was also markedly up-regulated after activation with lipopolysaccharide or anti-mu antibodies. The Fas protein was not detected on resting or activated lymphocytes obtained from MRL lpr/lpr mice. Together, these findings suggest that Fas plays a role in both thymic selection and T-cell survival in the periphery and that the accelerated autoimmunity in MRL lpr/lpr mice results from a defect in both of these pathways.
Collapse