The growth capacity of hematopoietic progenitor cells in severe neutropenia induced by famotidine

Summary In four cases of severe neutropenia of unknown origin we found a strong inhibition of the growth of granulocyte-macrophage (GM) progenitor cells. The development of GM colonies in culture (GM-CFU-c) was more than 80% reduced in comparison to the control group. In particular, the interleukin 3- (IL-3) and granulocyte macrophage colony-stimulating factor-(GM-CSF) dependent growth was affected; a combination of growth factors (IL-3, GM-CSF, and G-CSF, the granulocyte colony-stimulating factor) resulted in a less reduced growth. The findings were primarily compatible with drug-induced bone marrow failure. Among the medications given to the patients, famotidine, an H2-receptor blocker, was discussed as an agent which possibly triggers off this process. After the withdrawal of famotidine, in three cases a continual increase of the growth of GM precursors was detected, reaching the normal level 7–17 days later. In one case, further investigations of the progenitor cells could not be carried out due to the death of the patient, but the rapid increase of neutrophils in the peripheral blood after withdrawal of famotidine pointed to the recovery of hematopoiesis. In vitro studies showed that famotidine, depending on the dose, inhibits the single growth factor-dependent colony growth (IL-3, GM-CSF, or G-CSF) of bone marrow progenitors from a concentration as low as 10g/ml. With the combination of all three growth factors only slight inhibitory effects were detectable (up to 150g/ml famotidine). These results indicate that famotidine, in common with other H2-receptor antagonists, can affect hematopoietic progenitor cells. However, the plasma concentration of famotidine normally used in ulcer therapy does not seem to influence the hematopoiesis. Apparently, the progenitor cells of only a few patients possess a higher sensitivity to the blockade of H2-receptors at this concentration of famotidine. This was demonstrated in one case (patient 3) 2 years after the patient had recovered from famotidine-induced neutropenia. The growth of peripheral myeloid, erythroid, and multilineage progenitor cells of this patient was remarkably reduced even at famotidine concentrations of 0.1–5.0g/ml whereas in the control group no inhibition was detected at these famotidine concentrations. Again, the IL-3-dependent colony formation was more affected than in the case of the combination of IL-3, GM-CSF, and G-CSF. After the removal of accessory cells the inhibitory effect of famotidine persisted, demonstrating that accessory cells do not play a major role in this process.     

Successful treatment of autoimmune neutropenia with recombinant human granulocyte-colony stimulating factor (R-metHuG-CSF)

Autoimmune neutropenia (AIN) is characterized by antibody mediated peripheral destruction of neutrophils. Since there is no effective treatment, antibiotics have to be used frequently for recurrent infections. Five selected patients with serologically proven AIN were treated with r-metHuG-CSF at 5–8 μg/kg body weight (300–480 μg) daily; the dose and frequency of r-metHuG-CSF was reduced after neutrophil counts above 1.0×10⁹/l were obtained. R-metHuG-CSF is effective in AIN and causes a sustained rise in ANC which can be maintained on a low dose administered twice or thrice weekly.     

Agranulocytosis associated with "Mexican aspirin" (dipyrone): evidence for an autoimmune mechanism affecting multipotential hematopoietic progenitors

A case of acute, transient agranulocytosis and thrombocytopenia associated with ingestion of dipyrone is reported. This once widely used analgesic, which is now banned in the United States, was obtained by the patient as "aspirin" while traveling in Mexico. Studies of the effects of this patient's serum on purified CD34+ marrow cells, which were highly enriched for hematopoietic progenitors, showed not only a drug-dependent suppression of the in vitro growth of myeloid progenitors, as has been reported previously, but also a drug-dependent suppression of primitive multipotential progenitors (CFU-Mix) and erythroid progenitors (BFU-E). These findings indicate that autoimmune, antibody-hapten interactions which have been reported to occur in dipyrone- and aminopyrine-induced agranulocytosis are not restricted to the neutrophil lineage.     

Increased Frequency of Monoclonal Gammopathy of Undetermined Significance in Patients With Nonimmune Chronic Idiopathic Neutropenia Syndrome

This study describes the frequency of monoclonal gammopathy of undetermined significance (MGUS) and the changes in some inflammation-related serum proteins in 157 patients with nonimmune chronic idiopathic neutropenia syndrome (NI-CINS). Of these patients, 42 had pronounced neutropenia with neutrophil counts < 1500/microL, and 115 had mild neutropenia with neutrophil counts ranging from 1500 to 2499/microL. Sixty-six volunteers served as healthy control subjects and 157 age- and sex-matched patients hospitalized for nonmalignant diseases served as patient control subjects. We found that 28.6% of patients with pronounced neutropenia and 14.8% of patients with mild neutropenia had increased serum gamma globulins (above the 95% confidence limit of values of the control subjects). In the group of patients with pronounced neutropenia, 30.9% had increased immunoglobulin (Ig)G values and 23.8% had increased IgA values. In the group of patients with mild neutropenia, 17.4% had increased IgG values and 21.7% had increased IgA values. IgG and IgA values strongly correlated with the neutrophil count. No changes in serum IgM were found. Three of 42 patients with pronounced neutropenia (7.14%) and 3 of 115 patients with mild neutropenia (2.61%) had serum immunofixation tests which showed a small monoclonal spike--4 were IgG-kappa type, 1 was IgG-lambda type, and 1 was IgA-kappa type. None of the healthy or patient control subjects had any evidence of MGUS. No significant changes in the amount of monoclonal spikes were documented during an 18- to 143-month follow-up (median, 58 months). Except for significantly increased alpha1-antitrypsin levels, there were no significant differences in the levels of acute-phase proteins studied between the study patients and the control subjects. These findings are consistent with our previous report suggesting the possible existence of an unrecognized low-grade chronic inflammation in patients with NI-CINS, which may be involved in the pathogenesis of neutropenia in the affected subjects.     

Infection Rates in HIV-HCV Patients Treated with Interferon Are Similar to Those in HCV Mono-Infection and Not Related to Neutropenia

Abstract

Method: Infectious complications were assessed in 25 HIV-HCV coinfected patients receiving 29 courses of HCV therapy (786 person-weeks). Results: The infection rate (1.3 infections/100 person-weeks) was similar when compared to the rate in HIV-negative patients. HIV status and neutrophil nadir did not predict infection risk or rate. Conclusion: Interferon dose reduction and/or G-CSF in HCVtreated HIV patients with neutropenia are not justified.