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The antigenic profile and the proliferative pathways in leukemic cells from the patient TRT with T-prolymphocytic leukemia (T-PLL) were analyzed using monoclonal antibodies (MoAbs) and cytokines. T-PLL cells expressed the phenotype CD1- CD3+ CD4+ CD8+. Incubation with the differentiating agent phorbol-12-myristate-13-acetate markedly increased the percentage of cells with the CD4- CD8+ phenotype, suggesting that leukemic cells were already committed towards a differentiated element with the CD4- CD8+ phenotype. T-PLL cells were induced to proliferate by anti-CD2 MoAb 9–1 + 9.6 and by anti-CD3 MoAb OKT3. The two pathways exhibited normal functional interactions and were susceptible to modulation by anti-HLA class I MoAbs. These results indicate that regulation of cell proliferation was preserved to a significant extent in the T-PLL cells analyzed. At variance with normal resting T cells that require previous activation to proliferate when incubated with interleukin-1 (IL-1) or interleukin-2 (IL-2), T-PLL cells proliferated vigorously when incubated with either interleukin. Furthermore, T-PLL cells proliferated when incubated with immune interferon (IFN-gamma). The latter finding parallels the enhancement by IFN-gamma of the proliferative response of lectin-activated murine T lymphocytes. These results suggest that T-PLL cells, which express a high constitutive level of c-myc mRNA, may be in an activated state. The antigenic phenotype and the characteristics of the proliferative pathways of T-PLL cells from the patient TRT are compatible with the possibility that they may be derived from an intermediate thymocyte.

The antigenic profile and the proliferative pathways in leukemic cells from the patient TRT with T-prolymphocytic leukemia (T-PLL) were analyzed using monoclonal antibodies (MoAbs) and cytokines. T-PLL cells expressed the phenotype CD1-CD3+CD4+CD8\ Incubation with the differentiating agent phorbol-12-myristate-13-acetate markedly increased the percentage of cells with the CD4 CD8+phenotype, suggesting that leukemic cells were already committed towards a differentiated element with the CD4 CD8+phenotype. T-PLL cells were induced to proliferate by anti-CD2 MoAb 9-1+9.6 and by anti-CD3 MoAb OKT3. The two pathways exhibited normal functional interactions and were susceptible to modulation by anti-HLA class I MoAbs. These results indicate that regulation of cell proliferation was preserved to a significant extent in the T-PLL cells analyzed. At variance with normal resting T cells that require previous activation to proliferate when incubated with interleukin-1 (IL-1) or interleukin-2 (IL-2), T-PLL cells proliferated vigorously when incubated with either interleukin. Furthermore, T-PLL cells proliferated when incubated with immune interferon (IFN- γ). The latter finding parallels the enhancement by IFN- γof the proliferative response of lectin-activated murine T lymphocytes. These results suggest that T-PLL cells, which express a high constitutive level of c-mycmRNA, may be in an activated state. The antigenic phenotype and the characteristics of the proliferative pathways of T-PLL cells from the patient TRT are compatible with the possibility that they may be derived from an intermediate thymocyte. © 1989 by Grune & Stratton. Inc.