No abstract

The t(12;21) (p 13; q22) results in the fusion of the TEL gene located on chromosome 12 with the AML1 gene located on the derivative chromosome 21. Because this translocation is difficult to detect using standard cytogenetic techniques, 27 previously karyotyped B-lineage acute lymphoblastic leukemia (ALL) cell lines were evaluated for the presence of the TEL-AML1 fusion using the reverse transcriptase- polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and cDNA sequencing. Six cell lines expressed the TEL-AML1 chimeric transcript by RT-PCR and the t(12;21) was confirmed by FISH analysis with probes for TEL, AML1, and chromosome 12. While only one of the 6 cell lines with the t(12;21) lost the der(12)t(12;21)-encoded AML1-TEL fusion transcript, 4 cell lines lacked expression of the nontranslocated allele of TEL and 5 cell lines lacked expression of CDKN2. Moreover, in 2 patients (1 with the TEL-AML1 transcript and 1 without), TEL expression was lost with disease progression; le, TEL was expressed in the initial cell lines (established at diagnosis or first relapse) whereas TEL was not expressed in the cell lines established from these patients in late-stage disease. These data show the coexistence of multiple genetic defects in childhood B-lineage ALL Cell lines with t(12;21) will facilitate the study of TEL-AML1 and AML1-TEL fusion proteins as well as TEL and CDKN2 gene inactivation in leukemia transformation and progression.

The t(12;21) (p 13; q22) results in the fusion of the TEL gene located on chromosome 12 with the AML1 gene located on the derivative chromosome 21. Because this translocation is difficult to detect using standard cytogenetic techniques, 27 previously karyotyped B-lineage acute lymphoblastic leukemia (ALL) cell lines were evaluated for the presence of the TEL-AML1 fusion using the reverse transcriptase- polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and cDNA sequencing. Six cell lines expressed the TEL-AML1 chimeric transcript by RT-PCR and the t(12;21) was confirmed by FISH analysis with probes for TEL, AML1, and chromosome 12. While only one of the 6 cell lines with the t(12;21) lost the der(12)t(12;21)-encoded AML1-TEL fusion transcript, 4 cell lines lacked expression of the nontranslocated allele of TEL and 5 cell lines lacked expression of CDKN2. Moreover, in 2 patients (1 with the TEL-AML1 transcript and 1 without), TEL expression was lost with disease progression; le, TEL was expressed in the initial cell lines (established at diagnosis or first relapse) whereas TEL was not expressed in the cell lines established from these patients in late-stage disease. These data show the coexistence of multiple genetic defects in childhood B-lineage ALL Cell lines with t(12;21) will facilitate the study of TEL-AML1 and AML1-TEL fusion proteins as well as TEL and CDKN2 gene inactivation in leukemia transformation and progression.

Proliferation of T lymphocytes can be induced by IL-2, either through an autocrine pathway in which the responding cell produces its own IL-2 or through an exocrine pathway in which IL-2 secreted by Th stimulates proliferation of IL-2-dependent CTL. However, proliferation of at least some CTL clones, such as CTL L3 and CTL dB45, also can be induced by stimulation of the antigen receptor in the absence of IL-2. Stimulation of these cloned CTL with T cell-depleted allogeneic spleen cells, allogeneic tumor cells, or immobilized mAb reactive with the T cell antigen receptor (TCR) induced thymidine incorporation, entry into cell cycle, and secretion of macrophage activating factor, but these stimuli did not induce the secretion of IL-2. Several observations indicated that such proliferation of cloned CTL induced by stimulation of the TCR was independent of IL-2; IL-2 could not be detected in supernatants from stimulated CTL cells. mAbs reactive with the murine IL-2-R efficiently blocked IL-2-mediated thymidine incorporation in cloned CTL and Th, but had no inhibitory effect on TCR-driven thymidine incorporation in the CTL clones. TCR-driven thymidine incorporation in cloned Th L2 cells was profoundly inhibited by these antibodies, indicating the operation of an IL-2-mediated autocrine pathway for proliferation in this cloned Th. When antibodies to the TCR were used to stimulate cloned CTL and Th, IFN-gamma mRNA was easily shown in the cloned CTL and Th. Although IL-2 mRNA could be detected in the cloned Th, it was never observed in the cloned CTL. These findings provide evidence for the existence of a TCR-mediated, IL-2-independent pathway for induction of cellular proliferation in cloned murine CTL.

To obtain approval of an IND application, cord blood banks need a set of standard operating procedures that describe cord blood collection, processing, freezing, and storage. Issues relating to potential cord blood recipient identification, cord blood shipping, and reporting of transplant recipient outcomes are also needed. The IND process provides an opportunity for outside reviewers to make suggestions that may be included in the standard operating procedures.