Induction of CD8 antigen and suppressor activity by glucocorticoids in a CEM human leukemic cell clone.

The relationship between glucocorticoid effect and regulation of cell surface antigens was investigated in two models of leukemic cell lines, CEM C7 denoted (r+, ly+) and CEM C1 (r+, ly-). The reactivity of murine monoclonal antibodies, anti-CD4-FITC, anti-CD8-FITC, anti-CD2-FITC and anti-calla-FITC, were analyzed using flow cytometry. The suppressor function was determined using [3H]thymidine incorporation into phytohemagglutinin-activated peripheral blood lymphocytes. Dexamethasone treatment of a human leukemic cell clone CEM C7 caused an increase in a subset of cells expressing the surface antigen CD8, which is present on suppressor and cytotoxic T-lymphocytes. By comparison, there was no modification of the expression of CD4 antigen, which is expressed at high levels in these cells. After two days of treatment with 5 x 10(-8) M dexamethasone, CEM C7 cells showed a two-fold increase in suppressor activity compared to untreated cells. In contrast, there was no regulation by glucocorticoids of either the CD8 or CD4 antigens in the leukemic clone CEM C1. Furthermore, no modification of the suppressor function in CEM C1 cells by dexamethasone was observed. In the human leukemic cells studied here, the ability to induce CD8 antigen expression in a CD4+ cells correlates with the ability to induce cell lysis in a glucocorticoid receptor positive cell population.

Prediction of platelet production during chemotherapy of acute leukemia.

Mean megakaryocyte ploidy, mean platelet volume, and platelet count were measured during 17 courses of chemotherapy for acute nonlymphocytic leukemia. During the myelosuppression from chemotherapy, all three variables fell; during recovery, megakaryocyte ploidy rose 1-2 days before platelet volume, which in turn rose 1-2 days before platelet count. Serial platelet volumes and counts of these patients were compared to the nomogram of the inverse nonlinear relation between platelet count and platelet size in reference subjects. Platelet volume became inappropriately small before platelet count fell substantially and remained small through most of the thrombocytopenic nadir. The end of the nadir was predictable 1-2 days after platelet volume increased to lie congruent with the reference nomogram. Changes in thrombopoiesis appear to occur sequentially in megakaryocyte ploidy, platelet volume, and platelet count. Changes in platelet count, and therefore the appearance of duration of the thrombocytopenic nadir, can be predicted by 1-2 days with platelet volume and 3-4 days with megakaryocyte ploidy. As platelet count rose, despite the continuing predominance of "young" platelets, MPV fell, suggesting that megakaryocyte stimulation as well as platelet age affects platelet size.

Erythropoiesis during recovery from iron deficiency: normocytes and macrocytes.

In 26 patients with severe iron deficiency and microcytic anemia (MCV less than 70 fl), serial red cell size distribution histograms (erythrograms) were taken before and during iron therapy. Initially all patients had a single population of red cells, all microcytes. With the first reticulocytosis after iron therapy, a new population of cells appeared, larger in volume than the original. In 23 of 26 patients the new population of cells was of normal size (82-96 fl). In 3 of 26, the new population was macrocytic (MCV greater than 98 fl). Of these 3, 1 had folate deficiency; after folate was given, normocytes were produced. The other 2, both taking phenytoin and 1 a heavy alcohol using, had persistent macrocytosis despite folate administration. Erythrograms allowed quantitative, rapid evaluation of erythropoietic response to iron repletion. Abnormal macrocytic responses could be identified and seemed to occur with some frequency.

Erythropoiesis during recovery from macrocytic anemia: macrocytes, normocytes, and microcytes.

In seven patients with marked megaloblastic anemia (MCV greater than 110 fl), red cell size distribution curves (erythrograms) demonstrated the size of red cells produced after therapy. In six, the new red cells were normocytic throughout recovery. In the seventh patient, folate repletion along produced a new population of microcytes, due to unsuspected iron deficiency; after iron repletion normocytes were produced. Three patients with autoimmune hemolytic anemia had macrocytosis (MCV greater than 110 fl) without folate or vitamin B12 deficiency. During recovery with predisone therapy, instead of a discrete new normocytic population appearing, the entire population progressively returned to normal size. Normal rather than "stress" reticulocytes, and remodeled stress reticulocytes remaining, may explain this different pattern of recovery. Two patients initially had minor subpopulations of smaller red cells that disappeared soon after therapy. These probably reflected the dyserythropoiesis of severe megaloblastic anemia.