| Research Abstract |
Several series of the experiments were conducted to analyze the mechanisms underlying autoimmunity Induced by chronic graft-versus-host reaction (GVHR).
(1) ELISA spot assay was employed to investigate the mechanisms of autoantibody production by GVHR. Conventional antibody (ant-TNP, anti-OVA) producing cells were shown to be activated by GVHR as well as autoantibody (anti-DNA, iTA, etc) producing cells. Thus, It was suggested that autoantibody production might be associated with polyclonal B cell activation in chronic GVIIR.
(2) Electron microscopical examination on the glomerular lesion demonstrated electron dense deposits first In the mesangial matrix, then in the subepithellum compatible with Immune complex glomerulonephrltls. Subendothellal deposits were not observed. Immunofluorescent study revealed IgG deposition In the capillary wall and IgM in the mesanglum early In the process. Some glomerull showed segmental mesangiolysis, suggesting that altered mesangial cells have a role In
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the development of glomerular change, which together with rise In serum autoantibody titer suggest that autoantibodies promote the glomerular lesions In this model system.
(3) GVIIR was induced In BDF_1 and (BALB/cx A)F_1(CAF_1) murine recipients by Injection of their parental or B10. D2-derlved spleen cells. The lncridences of glomerulonephritis and autoantibody production were then correlated. All BDF_1 mice that received DBA/2 spleen cells (termed DBA/2->BDF_1) and 33% of CAF_1 mice that received BALB/c spleen cells (BALB/c->CAF_1) developed glomerulonephritis. However, In other combinations (B10. D2->BDF_1, A/J->CAF_1) no significant glomerular leslons were observed. Analysis of antibodies by ELISA has revealed that the groups with renal disease showed significant polyclonal elevaton of IgG-class antibodies, including autoantibodies (anti-DNA, anti-MRBC and NTA) and conventional antibody (antl-TNP-KLII). No significant IgG class antibody production was observed In the groups that did not develop glomerulonephritis. Thus, it was suggested that an IgM to IgG class switch is important In the development of glomerulonephritis In GVHR. Other factors appear to be involved. Only 33% of BALB/C->CAF_1 developed glomerulonephritis even though a level of IgG class antibody production was comparable to that observed In DBA/2->BDF_1 In which 100% showed severe glomerulonephritis.
(4) Myc and Raf gene expression was analysed and compared with B cell activity and cell kinetics. ELISA spot assay revealed transient B cell proliferation with a peak at 3 week after transfer. Mye and Raf genes showed the Increased expression wlth the peak at 3 weeks after transfer. This profile was consistent with that of B cell prollferation revealed by ELISA spot assay. Cell kinetics analysis revealed that proliferative cells In G2+M phase increased 4 weeks after transfer. Thus, the myc and raf activity has been considered to be correlated to the B cell activity. These oncogene activity Is considered to be correlated with abnormal lymphold cell proliferation from the lnvestigations on lymphold cell malignancy and spontaneous autoimmune model mouse. Since proliferative B cells In GVHR Is Intrinsically normal, the present findings seem to indicate In vivo evidence of Involvement of myc and raf gene In B cell proliferation.
(5) Microscopical examination revealed mononuclear cell Infiltration In pulmonary alveolar wall of DBA/2->BDF_1, suggesting the presence of mild degree of interstitial pneumonlae. Increase of lymphocytes and angotensin converting enzyme activity In bronchloalveolar lavage fluid was consistent with this notion. Pathological change in the lungs of DBA/2->BDF_1 was suggested to be a model of interstitial pneumonia. Less
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