Development of blast transformation after serial passage. (A) Cartoon showing disease development in recipients of cells from serial passage. Secondary recipients (A1 through 5) received a 1:1 mixture of spleen and bone marrow cells from mouse H2. Spleen or bone marrow cells were transferred to tertiary recipients. Only mice receiving the spleen cells developed the myeloproliferative disease. All mice receiving bone marrow cells developed T-cell lymphomas with characteristics similar to H2A4B1. Cells derived from the spleen of tertiary recipients that developed the myeloproliferative disease were transferred to quaternary recipients. All of these mice developed T-cell lymphomas. (B) Proviral integration pattern shows a common single proviral integration site in all H2 mice. Lanes 1 and 2 are from primary mice. Lanes 3 through 8 are from secondary mice. (C) Both the myeloproliferative disease and T-cell lymphomas show an identical proviral integration pattern. Lanes 2 through 4 are derived from T-ALL. Lanes 5 through 7 are secondary and tertiary recipients. (D) Tissues from the H2 mice show the presence of an intact integrated provirus. For (B) and (C), genomic DNA was digested with EcoRI and genomic DNA shown in (D) was digested with Xba I. The blots were hybridized with the cDNA expressing the neomycin resistance gene.