In vitro medullary granulocytic progenitor (CFUc) cultures from 6 cases of granulocytopenias

Alternative testing systems for evaluating noncarcinogenic, hematologic toxicity

Hematopoietic tissues are the targets of numerous xenobiotics. Clinical hematotoxicity is either a decrease or an increase in peripheral blood cell counts in one or more cell lineages--a cytopenia or a cytosis, respectively--that carries a risk of an adverse clinical event. The purpose of in vitro hematotoxicology is the prediction of these adverse hematologic effects from the effects of the toxicants on human hematopoietic targets under controlled experimental conditions in the laboratory. Building on its important foundations in experimental hematology and the wealth of hematotoxicology data found in experimental oncology, this field of alternative toxicology has developed rapidly during the past decade. Although the colony-forming unit-granulocyte/monocyte neutrophil progenitor is most frequently evaluated, other defined progenitors and stem cells as well as cell types found in the marrow stroma can be evaluated in vitro. End points have been proposed for predicting toxicant exposure levels at the maximum tolerated dose and the no observable adverse effect level for the neutrophil lineage, and several clinical prediction models for neutropenia have developed to the point that they are ready for prospective evaluation and validation in both preclinical species and humans. Known predictive end points are the key to successful comparisons across species or across chemical structures when in vitro dose-response curves are nonparallel. Analytical chemistry support is critical for accurate interpretation of in vitro data and for relating the in vitro pharmacodynamics to the in vivo pharmacokinetics. In contrast to acute neutropenia, anemia and acute thrombocytopenia, as well as adverse effects from chronic toxicant exposure, are much more difficult to predict from in vitro data. Pharmacologic principles critical for clinical predictions from in vitro data very likely will apply to toxicities to other proliferative tissues, such as mucositis.

Drug-induced agranulocytosis: evidence for the commitment of bone marrow haematopoiesis

Clinical and haematological features of 61 patients with drug-induced agranulocytosis (63 episodes) are presented. Multiple drug consumption was a common observation and complicated the attempt to incriminate a particular drug as being aetiologically involved. Bone marrow analysis shortly after the diagnosis revealed evidence for an impairment of proliferative granulopoiesis in the majority of cases. This observation was confirmed by in vitro culturing of granuloid precursor cells (CFU-c). Moreover, the data clearly demonstrated that drug-induced agranulocytosis may not be restricted to the granulocytic series. Thrombocytosis and reticulocytosis during the recovery phase are taken as an indication for the commitment of all haemopoietic cell lineages in agranulocytosis. These observations were in accordance with cytomorphological studies and in vitro culture data of erythroid precursor cells (CFU-e, BFU-e) of bone marrow aspirates taken in the initial phase of agranulocytosis. More than 25% of the patients showed a marked erythroid depression in the marrow.

Procainamide-induced agranulocytosis with reversible myeloid sensitivity

A 56-year-old man developed procainamide-induced agranulocytosis. Bone marrow aspiration showed the absence of myeloid elements beyond the promyelocyte stage. Procainamide at therapeutic concentrations in vitro depressed bone marrow granulocyte-macrophage colonies (CFUc) while CFUc growth was normal in the absence of drug. Following the patient's recovery, CFUc growth was no longer suppressed by procainamide in vitro. The observations in this patient showing reversible sensitivity to drug contrast with those on other patients with drug-induced agranulocytosis that show persistent marrow injury or drug sensitivity despite clinical recovery.

Hematologic effects of antipyretic analgesics. Drug-induced agranulocytosis

Drug-induced agranulocytosis may be type I (involving the drug, antibodies and neutrophils), type II (associated with accumulated drug toxicity in hypersensitive persons), or type III (representing different etiologies induced by immune and toxic mechanisms). The pyrazolones (amidopyrine, dipyrone and butazones), phenothiazine derivatives, antithyroid drugs, and antibiotics are thought to be causative agents in agranulocytosis. The symptoms may involve sudden onset of high fever, sore throat with ulcerative angina, or stomatitis. Diagnosis of agranulocytosis is confirmed by severe granulocytopenia (0-0.5 X 10(9)/l), but bone marrow examination is required to rule out aplastic anemia and cancer. Treatment of drug-induced agranulocytosis involves immediate withdrawal of the incriminated drug. In most patients, granulocyte, reticulocyte, and thrombocyte cell counts overshoot in the regenerative phase of drug-induced agranulocytosis.