ELISA titers of autoantibodies against nuclear antigens (histone/dsDNA) in transplanted mice.

(A) Sera from C57BL/6 recipients of TβRII^−/− bone marrow were analyzed by ELISA at 4 weeks after transplantation. The 10 recipients (5 + 5) received bone marrow from 2 donors, as distinguished by filled and empty circles. We analyzed 9 animals. (B) All animals except one were, in addition, analyzed at the terminal stage of inflammatory disease (ie, 6 to 9 weeks after transplantation). Values obtained from the same animal at the 2 time points are connected with a line. (C) As controls, sera were taken from recipients of TβRII^+/− bone marrow derived from induced TβRII+/flox × Mx1-Cre donor mice. (D) In addition, 3 nontransplanted C57BL/6 mice were included as controls for transplantation artifacts. A positive control (serum from the MRL-lpr strain; a mouse model of the human autoimmune disease lupus erythematosus) showed a reference value of 1.8. Mean values are indicated by horizontal lines. Comparisons between experimental animals at 4 weeks after transplantation and transplanted controls were statistically significant (P ≤ .022) using the 2-tailed Student t test. The higher titers at the terminal stage of disease compared with controls were, however, not statistically significant. For titer definition, see “Materials and methods.”