Relative deficiency in the in vitro proliferation of helper phenotype T cells from individuals with T cell leukemias

Mononuclear cells from blood patients with T cell acute lymphoblastic leukemia (T-ALL) or T-hairy cell leukemia (T-HCL), regardless of the phenotype of the leukemic cells, revealed a progressive increase in the proportion of Leu2T8⁺ cells upon culture with PHA and TCGF. From less than 5% at Day 0 in culture, Leu2T8⁺ cells increased to 10-25% on day 3. By day 7 levels ranged from 27-84%, with a greater than fourfold predominance of Leu2T8⁺ cells over Leu3T4⁺ cells as demonstrated by two color immunofluorescence in flow cytometry. In contrast, the predominance of Leu3T4⁺ cells (60-70%) was stable in stimulated culture of normal mononuclear cells. Evidence that the Leu2T8⁺ cells cultured from individuals with T-leukemia are normal T cells is: 1) Karyotype studies on the one individual with abnormal chromosomes in leukemic cells showed normal 46 XX chromosome complements in cultured PACS-isolated Leu2T8⁺ cells. 2) Uncultured T cells from a patient with T-ALL showed a type G6PD. Within 6 days in culture, 72% of cells expressed the Leu2T8⁺ phenotype and both G6PD enzymes A and B were observed in a ratio of 60:40. These results demonstrate that Leu2T8⁺ cells have an in vitro proliferation advantage over neoplastic T cells. Of greater interest, Leu3T4⁺ cells from leukemics show greatly decreased proliferation reflecting either a proliferative defect or a deficiency in the number of Leu3 cells.