ALBERT

Description: Human gamma interferon (HuIFN gamma) was evaluated for its effects on the release from human peripheral blood T lymphocytes (greater than 98% pure) stimulated by phytohemagglutinin (PHA) of activities that can stimulate granulocyte-macrophage (CFU-GM) colonies and clusters, erythroid (BFU-E) bursts, and mixed (CFU-GEMM) colonies. T lymphocytes did not release these activities in the absence of PHA with or without HuIFN gamma. In the presence of PHA, pure natural HuIFN gamma at concentrations of 0.1 to 100 U/mL significantly enhanced release of these colony-stimulating activities. Although enhanced release of granulocyte-macrophage colony-stimulating activities were noted when T lymphocytes were added to the conditioning medium in the presence of 0.1%, 0.5%, and 1% PHA, enhanced release of burst-promoting and mixed colony activities was seen only in the presence of 0.1% and 0.5% PHA. The enhanced release of colony-stimulating activities was not due to HuIFN gamma-suppression of the release from PHA-stimulated T lymphocytes of suppressor molecules. The enhancing effects of natural HuIFN gamma were neutralized with a monoclonal anti-natural HuIFN gamma, and recombinant HuIFN gamma mimicked the enhancing effects of the natural HuIFN gamma. This enhancing effect was noted only when HuIFN gamma was added with the T lymphocytes and PHA during the first 24 hours of incubation. T lymphocytes were separated into T4+, T8-, T8+, and T4- subsets (greater than 98% pure for the appropriate phenotypes) after incubation with OKT4- and OKT8- monoclonal antibodies and sorting on a fluorescence-activated cell sorter (FACS). All types of colony-stimulating activities were released from each population after stimulation with PHA, but enhanced release of these activities in the presence of HuIFN gamma was only detected with the T4+ or T8- subsets of lymphocytes. It cannot be concluded from these studies whether HuIFN gamma is enhancing the release of one or several types of colony-stimulating activities, but these studies suggest a role for HuIFN gamma and T4+ lymphocyte subsets in the regulation in vitro of the release of colony-stimulating activities.

Description: Human gamma interferon (HuIFN gamma) was evaluated for its effects on the release from human peripheral blood T lymphocytes (greater than 98% pure) stimulated by phytohemagglutinin (PHA) of activities that can stimulate granulocyte-macrophage (CFU-GM) colonies and clusters, erythroid (BFU-E) bursts, and mixed (CFU-GEMM) colonies. T lymphocytes did not release these activities in the absence of PHA with or without HuIFN gamma. In the presence of PHA, pure natural HuIFN gamma at concentrations of 0.1 to 100 U/mL significantly enhanced release of these colony-stimulating activities. Although enhanced release of granulocyte-macrophage colony-stimulating activities were noted when T lymphocytes were added to the conditioning medium in the presence of 0.1%, 0.5%, and 1% PHA, enhanced release of burst-promoting and mixed colony activities was seen only in the presence of 0.1% and 0.5% PHA. The enhanced release of colony-stimulating activities was not due to HuIFN gamma-suppression of the release from PHA-stimulated T lymphocytes of suppressor molecules. The enhancing effects of natural HuIFN gamma were neutralized with a monoclonal anti-natural HuIFN gamma, and recombinant HuIFN gamma mimicked the enhancing effects of the natural HuIFN gamma. This enhancing effect was noted only when HuIFN gamma was added with the T lymphocytes and PHA during the first 24 hours of incubation. T lymphocytes were separated into T4+, T8-, T8+, and T4- subsets (greater than 98% pure for the appropriate phenotypes) after incubation with OKT4- and OKT8- monoclonal antibodies and sorting on a fluorescence-activated cell sorter (FACS). All types of colony-stimulating activities were released from each population after stimulation with PHA, but enhanced release of these activities in the presence of HuIFN gamma was only detected with the T4+ or T8- subsets of lymphocytes. It cannot be concluded from these studies whether HuIFN gamma is enhancing the release of one or several types of colony-stimulating activities, but these studies suggest a role for HuIFN gamma and T4+ lymphocyte subsets in the regulation in vitro of the release of colony-stimulating activities.

Description: A new and rare type of Bcr/Abl junction between exon C3 of the 3′ portion of the Bcr gene and Abl exon 2 has been identified in the leukemic cells of two Ph1-positive chronic myelogenous leukemia patients in chronic phase. This is the fourth type of Bcr/Abl junction so far identified in Ph1-positive hematologic malignancies and is a consequence of an unusual breakpoint position on chromosome 22 that falls approximately 20 kb downstream of the major breakpoint cluster region (bcr) of the Bcr gene. The new hybrid mRNA is 540 base pairs (bp) longer than that expressed by the K562 cell line and could codify for a Bcr/Abl protein carrying 180 additional aminoacids with respect to the larger P210 protein so far identified. The hematologic phenotype expressed by the two patients carrying this unusual type of Bcr/Abl rearrangement does not significantly differ from that commonly seen in chronic myelogenous leukemia.

Description: A new and rare type of Bcr/Abl junction between exon C3 of the 3′ portion of the Bcr gene and Abl exon 2 has been identified in the leukemic cells of two Ph1-positive chronic myelogenous leukemia patients in chronic phase. This is the fourth type of Bcr/Abl junction so far identified in Ph1-positive hematologic malignancies and is a consequence of an unusual breakpoint position on chromosome 22 that falls approximately 20 kb downstream of the major breakpoint cluster region (bcr) of the Bcr gene. The new hybrid mRNA is 540 base pairs (bp) longer than that expressed by the K562 cell line and could codify for a Bcr/Abl protein carrying 180 additional aminoacids with respect to the larger P210 protein so far identified. The hematologic phenotype expressed by the two patients carrying this unusual type of Bcr/Abl rearrangement does not significantly differ from that commonly seen in chronic myelogenous leukemia.

Description: In 26 myeloid and lymphoid acute leukemia patients at presentation the capacity to generate interleukin-2 (IL-2)-induced lymphokine-activated killer (LAK) cells effective against the natural killer (NK)-resistant Raji cell line, as well as the susceptibility of the blasts to normal peripheral blood (PB) LAK cells and to autologous LAK effectors was analyzed. The overall PB LAK activity against Raji cells was significantly lower in acute leukemia patients compared with normal controls (mean, 1,473 +/- 971 SD LU/10(8) LAK effectors v 3,340 +/- 1,862; P less than .001). The sensitivity of the blasts to autologous LAK cells was also significantly lower than to normal LAK effectors (517 +/- 593 LU/10(8) LAK effectors v 1,304 +/- 1,066; P less than .01). When the data were analyzed independently, four patterns of behavior could be recognized. The relatively largest group (9 of 26) included patients in whom effective LAK cells could be generated against the Raji line, but in whom the blasts were resistant to autologous PB-LAK effectors while being susceptible to normal LAK cells (defective specific LAK activity). In 5 of 26 cases, an incapacity to generate LAK activity against both allogeneic and autologous target cells was observed (defective LAK generation). In six further cases, the blasts were resistant to both allogeneic and autologous LAK populations, though the latter were effective against the Raji line (resistant blasts). The same defects could also be shown with bone marrow-derived LAK cells. Only in six cases did the leukemic blasts appear susceptible to autologous and allogeneic LAK cells. In four patients the analysis could be repeated at remission, and in three a restoration of the LAK function against the primary blasts was recorded. In the 10 cases studied at relapse, the blasts were resistant to autologous LAK effectors in nine and to normal LAK in seven. These data demonstrate that in most acute leukemia patients with active disease, a defect of the LAK machinery, either a deficient generation of LAK cells or the resistance of the blasts to LAK effectors, may be documented, pointing therefore to a possible contributory role of the LAK system in the control of leukemic cell growth. In view of the frequent normalization of the autologous LAK activity at the time of remission, immunotherapy with IL-2/LAK cells should be primarily aimed to patients with minimal residual disease.

Description: In 26 myeloid and lymphoid acute leukemia patients at presentation the capacity to generate interleukin-2 (IL-2)-induced lymphokine-activated killer (LAK) cells effective against the natural killer (NK)-resistant Raji cell line, as well as the susceptibility of the blasts to normal peripheral blood (PB) LAK cells and to autologous LAK effectors was analyzed. The overall PB LAK activity against Raji cells was significantly lower in acute leukemia patients compared with normal controls (mean, 1,473 +/- 971 SD LU/10(8) LAK effectors v 3,340 +/- 1,862; P less than .001). The sensitivity of the blasts to autologous LAK cells was also significantly lower than to normal LAK effectors (517 +/- 593 LU/10(8) LAK effectors v 1,304 +/- 1,066; P less than .01). When the data were analyzed independently, four patterns of behavior could be recognized. The relatively largest group (9 of 26) included patients in whom effective LAK cells could be generated against the Raji line, but in whom the blasts were resistant to autologous PB-LAK effectors while being susceptible to normal LAK cells (defective specific LAK activity). In 5 of 26 cases, an incapacity to generate LAK activity against both allogeneic and autologous target cells was observed (defective LAK generation). In six further cases, the blasts were resistant to both allogeneic and autologous LAK populations, though the latter were effective against the Raji line (resistant blasts). The same defects could also be shown with bone marrow-derived LAK cells. Only in six cases did the leukemic blasts appear susceptible to autologous and allogeneic LAK cells. In four patients the analysis could be repeated at remission, and in three a restoration of the LAK function against the primary blasts was recorded. In the 10 cases studied at relapse, the blasts were resistant to autologous LAK effectors in nine and to normal LAK in seven. These data demonstrate that in most acute leukemia patients with active disease, a defect of the LAK machinery, either a deficient generation of LAK cells or the resistance of the blasts to LAK effectors, may be documented, pointing therefore to a possible contributory role of the LAK system in the control of leukemic cell growth. In view of the frequent normalization of the autologous LAK activity at the time of remission, immunotherapy with IL-2/LAK cells should be primarily aimed to patients with minimal residual disease.