Autoimmune neutropenia in pregnant women causing neonatal neutropenia

Autoimmune neutropenia (AIN) can occur during pregnancy. However, neonatal neutropenia occurring in an infant born to a mother with AIN has only rarely been documented. Recently, we have experienced two cases of AIN during pregnancy, both of which caused severe yet transient neonatal neutropenia (< 0.3 x 10(9)/l), probably as a result of transplacental maternal anti-neutrophil autoantibodies. The anti-neutrophil antibodies seemed to be against antigens other than NA1/NA2 because the autoantibodies did not bind to neutrophils of specific NA types selectively in the granulocyte indirect immunofluorescence test. Although AIN is a relatively uncommon disease, neonatal neutropenia caused by maternal AIN may not be quite as rare.     

Reversal of neutropenia with intravenous gammaglobulin in autoimmune neutropenia of infancy

Intravenous gammaglobulin (IVIgG) was used to treat autoimmune neutropenia of infancy in two males with repeated infections. The neutrophil count increased significantly in both patients with the initial IVIgG therapy; 1 patient went into remission. The neutrophil count in the other remained above baseline for 3 wk, and a subsequent booster infusion also caused the neutrophil count to increase. The patients have remained clinically well since their treatment began. Serial studies of antineutrophil antibody and serum lysozyme, performed to elucidate the mechanism of action, suggested decreased neutrophil destruction, perhaps by Fc receptor blockade, as well as decreased synthesis of antineutrophil antibody. Neutrophil function was not impaired after the neutrophil count increased. Many patients with immune neutropenia have a benign course, but those who have significant infections could be treated, acutely or prophylactically, with intravenous gammaglobulin.     

Cyclic neutropenia in mammals

Cyclic neutropenia (CN) has been well documented in humans and the gray collie. A recent model of the architecture and dynamics of hematopoiesis has been used to provide insights into the mechanism of cycling of this disorder. It provides a link between the cycling period and the cells where the mutated ELA2 is expressed. Assuming that the biologic defect in CN is the same in dogs, and the observation that the structure of hematopoiesis is invariant across mammals, we use allometric scaling techniques to correctly predict the period of cycling in the gray collie and extend it to other mammals from mice to elephants. This work provides additional support for the relevance of animal models to understand disease but cautions that disease dynamics in model animals are different and this has to be taken into consideration when planning experiments.     

Cyclic neutropenia

Cyclic neutropenia is a rare hematologic disorder, characterized by repetitive episodes of fever, mouth ulcers, and infections attributable to recurrent severe neutropenia. Fluctuations in blood cells are due to oscillatory production of cells by the bone marrow. Recent genetic, molecular, and cellular studies have shown that autosomal-dominant cyclic neutropenia and sporadic cases of this disease are due to a mutation in the gene for neutrophil elastase (ELA2), located at 19p13.3. This enzyme is synthesized in neutrophil precursors early in the process of primary granule formation. It is currently presumed that the mutant neutrophil elastase functions aberrantly within the cells to accelerate apoptosis of the precursors, resulting in effective and oscillatory production. Cyclic neutropenia is effectively treated with granulocyte colony-stimulating factor (G-CSF), usually at doses of 1 to 5 microg/kg/d (median dose, 2.5 microg/kg/d). Long-term, daily, or alternate-day administration reduces fever, mouth ulcers, and other inflammatory events associated with this disorder. Leukemic transformation is not a recognized risk for cyclic neutropenia, with or without treatment with G-CSF.     

Cyclic neutropenia

Summary A 21 year old male has been followed for 2 years with periodic neutropenia and no evidence of underlying disease. Lymphocytosis and hypergammaglobulinemia suggested the possibility of a humoral marrow depressant. But, no such factor could be identified in a limited crude experiment. Furthermore, our patient did not improve after splenectomy or therapy with testosterone or corticosteroids.

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Zusammenfassung Bei einem 21jährigen Patienten wurde 2 Jahre lang eine periodische Neutropenie beobachtet ohne Zeichen einer Primärkrankheit. Lymphozytose und Hypergammaglobulinämie ließen auf die Möglichkeit einer humoralen markdepression schließen. Dieser Verdacht konnte aber nicht bestätigt werden. Weder eine Splenektomie noch die Therapie mit Testosteron oder Kortikoiden brachten eine Besserung.

     

The kinetics of colony formation by CFU-GM in vitro

Summary. Video-recordings of whole normal bone marrow granulocyte-macrophage colony (CFU-GM) cultures were made after 7, 14 and 21 d. Retrospective viewing of the tapes allowed the relationships to each other of the colonies scored on the three different occasions to be documented. The results show that, according to our scoring criteria, there is very little overlap between the numbers of colonies scored on days 7. 14 and 21. Moreover. only about 10% of the progenitors in a sample form day 21 colonies. The remaining progenitors form colonies earlier in the culture period and either disappear before day 21 or remain small.     

Congenital neutropenia

Congenital neutropenia is strictly defined as neutropenia present at birth. However, it is more generally used to describe neutropenia secondary to inherited genetic mutations. This review will discuss the presentation of such children and the various causes of congenital neutropenia. In particular, it will focus on severe congenital neutropenia (SCN) and the recent discovery of mutations in the gene encoding neutrophil elastase in the majority of cases of SCN. The potential mechanisms of pathogenesis and of transformation to leukaemia will be discussed. Shwachman-Diamond Syndrome and other less common causes of congenital neutropenia will also be reviewed. Finally, an approach to the child with potential congenital neutropenia will be presented.     

Responsiveness of highly enriched CFU-GM subpopulations from bone marrow, peripheral blood, and cord blood to hemopoietic growth inhibitors.

Human early and late granulocyte-monocyte progenitors (granulocyte-macrophage colony-forming units, CFU-GM), depleted of accessory cells, were physically separated using an antimyeloid monoclonal antibody (DS1.1). They were separately cultured at optimal growth conditions and tested for responsiveness to prostaglandin E2 (PGE2), recombinant tumor necrosis factor alpha (TNF alpha), and transforming growth factor beta-1 (TGF beta 1). Late (DS1.1+) CFU-GM displayed the highest sensitivity to PGE2 and TNF alpha, the first significant inhibition being evident at 10(-9)M PGE2 and 1 U/ml TNF alpha. Conversely, their growth was stimulated (211%-217%) by 0.25-2.5 ng/ml TGF beta 1. Early (DS1.1-) marrow CFU-GM evidenced a lower sensitivity to PGE2 and TNF alpha. Their growth, however, was inhibited by 0.25-2.5 ng/ml TGF beta 1. Early CFU-GM constitute the totality of peripheral blood myeloid progenitors. Cord blood CFU-GM were also demonstrated here to be entirely DS1.1-. Both adult and cord blood CFU-GM displayed the highest resistance to PGE2 and TNF alpha. By contrast, they showed the maximum sensitivity to growth inhibition by TGF beta 1, active at 0.025-0.25 ng/ml. For the first time, therefore, highly purified subsets of human CFU-GM were separated that displayed a different responsiveness to well-defined growth-regulatory molecules. Our results indicate that TGF beta 1 has a dual activity; it is inhibitory on early and stimulatory on late CFU-GM, whereas PGE2 and TNF alpha preferentially inhibit late CFU-GM growth.     

Differential expression of HLA-DR antigens in subsets of human CFU-GM

Expression of HLA-DR surface antigens by granulocyte/monocyte colony- forming cells (CFU-GM) may be important in the regulation of proliferation of these cells. Using immunological techniques to enrich for progenitor cells, we investigated the expression of HLA-DR in subsets of CFU-GM. "Early" (day 14) CFU-GM express higher levels of HLA- DR than do "late" (day 7) CFU-GM. Among late CFU-GM, cells destined to form monocyte (alpha-naphthyl acetate esterase-positive) colonies express higher levels of HLA-DR than do CFU-GM destined to form granulocyte (chloroacetate esterase-positive) colonies. Because high- level expression of DR antigen was a marker for monocyte differentiation, we examined several lymphokines for their effects on both DR expression and in vitro commitment to monocyte differentiation by myeloid precursor cells. DR antigen density could be increased by more than twofold over 48 hours upon exposure to gamma-interferon (gamma-IFN), whereas colony-stimulating factors had no effect. This was associated with a dose-dependent inhibition of total CFU-GM number, and a relative, but not absolute, increase in the ratio of monocyte colonies to granulocyte colonies. Similarly, in day 7 suspension cultures of purified myeloid precursor cells, gamma-IFN inhibited cell proliferation and increased the ratio of monocytes to granulocytes. Thus, despite the induction of high levels of HLA-DR antigen on precursor cells (a marker of monocyte commitment), the dominant in vitro effect of gamma-IFN was inhibition of granulocyte differentiation.     

Neutrophil marrow cellularity in neutropenia

In order to identify individuals in whom marrow abnormalities might be contributing to or responsible for neutropenia, we quantitatively examined the number and distribution of cells comprising neutrophil marrow in patients with blood neutrophils less than 2,000/μl. Neutrophil marrow cellularity was determined from ferrokinetic estimation of normoblast numbers and neutrophil-normoblast ratios obtained from marrow biopsy sections. Only two of 30 patients exhibited the change in cellularity expected of a normal marrow responding to removal of circulating neutrophils: reduced numbers of segmented cells, an expanded mitotic pool, and a normal ratio of metamyelocytes and band forms to promyelocytes and myelocytes. Twenty-three patients had basal mitotic pool size or increased numbers of segmented marrow cells despite neutropenia, a hypoplastic mitotic pool, or a reduction in the number of metas and bands relative to promyelocytes and myelocytes. The results in individual patients were consistent with hypoplasia, subnormal proliferative or release responses, loss of cells during ontogeny, or combinations thereof. In five cases the results could not be so classified. Clinical observations seldom predicted marrow cellularity. Diverse disorders of marrow function appear to be common among neutropenic patients. Neutropenia constitutes a rich field for study of neutrophil marrow physiology.     

Cyclic neutropenia in identical twins

Cyclic neutropenia developed in identical twin girls. The onset of neutropenia in these children occurred three years apart. Neutrophil cycling diminished, and symptoms decreased in the initially affected twin during a five-year follow-up. Some cases of cyclic neutropenia may be genetically determined; however, the onset and clinical manifestations may be modified by other internal and external factors. There may also be a prodromal period during which neutrophils cycle, but the patient is neither neutropenic nor symptomatic.