Anti-granulocyte opsonic activity and autoimmune neutropenia

Refractory Adult Primary Autoimmune Neutropenia that Responded to Alemtuzumab

Primary autoimmune neutropenia (P-AIN) is an extremely rare disease. The most effective treatment for primary P-AIN is a granulocyte colony-stimulating factor; however, no curative treatment has been reported. We herein report a case of an adult P-AIN patient with a relatively mild medical history (irrespective of the severe neutropenia) who showed a sustained hematological response over seventeen months after the initiation of treatment with subcutaneous Alemtuzumab.

Antineutrophil cytoplasmic antibodies, autoimmune neutropenia, and vasculitis

OBJECTIVES

Reports of an association between antineutrophil cytoplasmic antibodies (ANCA) and autoimmune neutropenia have rarely included cases of proven vasculitis. A case of ANCA-associated vasculitis (AAV) with recurrent neutropenia is described and relevant literature on the association between ANCA, neutropenia, and vasculitis is reviewed.

METHODS

Longitudinal clinical assessments and laboratory findings are described in a patient with AAV and recurrent episodes of profound neutropenia from December 2008 to October 2010. A PubMed database search of the medical literature was performed for articles published from 1960 through October 2010 to identify all reported cases of ANCA and neutropenia.

RESULTS

A 49-year-old man developed recurrent neutropenia, periodic fevers, arthritis, biopsy-proven cutaneous vasculitis, sensorineural hearing loss, epididymitis, and positive tests for ANCA with specificity for antibodies to both proteinase 3 and myeloperoxidase. Antineutrophil membrane antibodies were detected during an acute neutropenic phase and were not detectable in a postrecovery sample, whereas ANCA titers did not seem to correlate with neutropenia. An association between ANCA and neutropenia has been reported in 74 cases from 24 studies in the context of drug/toxin exposure, underlying autoimmune disease, or chronic neutropenia without underlying autoimmune disease. In these cases, the presence of atypical ANCA patterns and other antibodies were common; however, vasculitis was uncommon and when it occurred was usually limited to the skin and in cases of underlying toxin exposure.

CONCLUSIONS

ANCA is associated with autoimmune neutropenia, but systemic vasculitis rarely occurs in association with ANCA and neutropenia. The interaction between neutrophils and ANCA may provide insight into understanding both autoimmune neutropenia and AAV.

The use of interferon-gamma-treated U937 cells in chemiluminescence assays to detect red cell, platelet and granulocyte antibodies of potential clinical significance

The chemiluminescent (CL) response of interferon-gamma-treated U937 (IFN-U937) cells to sensitized target cells has been used to detect red cell, platelet and granulocyte antibodies. A clone of U937 cells was selected which expressed Fc receptor I (Fc gamma RI) and which, after incubation with IFN-gamma for 72 h, was capable of generating high levels of lucigenin-enhanced CL. The CL responses of IFN-U937 cells and peripheral blood human monocytes to sensitized red cells, platelets or granulocytes were then compared. Assays using monocytes or IFN-U937 cells were of comparable sensitivity for detection of antibodies against all three types of target cell. In addition, the use of IFN-U937 cells reduced interassay variation and simplified assay performance. The potential clinical usefulness of these CL assays was suggested by the ability of both monocytes and IFN-U937 cells to respond to red cells, platelets or granulocytes sensitized with sera from pregnant women whose babies had either haemolytic disease of the newborn (HDN), alloimmune thrombocytopenia or alloimmune neutropenia respectively. In addition, monocytes and IFN-U937 cells both responded to red cells sensitized with antibodies against a variety of specificities of assumed (although not documented) clinical significance for blood transfusion recipients. In contrast, monocytes and IFN-U937 cells responded only weakly to red cells sensitized with either anti-D in sera from mothers of babies unaffected by HDN, or with antisera containing high titre antibodies with specificities not normally associated with significantly reduced red cell survival.

Primary and secondary autoimmune neutropenia

Antineutrophil antibodies are well recognized causes of neutropenia, producing both quantitative and qualitative defects in neutrophils and increased risk for infection. In primary autoimmune neutropenia (AIN) of infancy, a moderate to severe neutropenia is the sole abnormality; it is rarely associated with serious infections and exhibits a self-limited course. Chronic idiopathic neutropenia of adults is characterized by occurrence in late childhood or adulthood, greater prevalence among females than among males, and rare spontaneous remission. Secondary AIN is more commonly seen in adults and underlying causes include collagen disorders, drugs, viruses and lymphoproliferative disorders. In most patients with AIN, antibodies recognize antigens located on the IgG Fc receptor type 3b but other target antigens have been recently identified in secondary AIN. Granulocyte colony-stimulating factor is a proven treatment in patients with AIN of all types and is now preferred to other possible therapies.

Autoimmune neutropenia manifesting as recurrent oral ulceration

There are many causes of recurrent oral mucosal ulceration, particularly gastrointestinal, mucocutaneous, and hematologic disease. The present report details the features of a patient with recurrent oral ulceration caused by autoimmune neutropenia.

Prospective evaluation of the chemiluminescence test for the detection of granulocyte antibodies: comparison with the granulocyte immunofluorescence test

A series of 213 neutropenic patients were tested for the presence of granulocyte antibodies using the granulocyte chemiluminescence test (GCLT) and the granulocyte immunofluorescence test (GIFT). Sera containing lymphocyte (HLA) antibodies were excluded from the study. A direct GIFT was performed on granulocytes from 56 patients. Samples were obtained from patients with a range of clinical conditions including primary adult autoimmune neutropenia, autoimmune neutropenia of infancy, autoimmune neutropenia secondary to Felty's syndrome, rheumatoid arthritis, idiopathic thrombocytopenic purpura, systemic lupus erythematosus, proliferative disorders, bone marrow transplantation and patients with documented febrile or pulmonary transfusion reactions. Overall, granulocyte antibodies were detected in 52.1% of patient sera. Results for the GCLT and GIFT (IgG) were strongly correlated (p < 0.001) for both primary and secondary immune neutropenias. The results confirm the applicability of the GCLT in the granulocyte serology laboratory.

Evaluation of the mechanisms of antiepileptic drug-related chronic leukopenia

Antiepileptic drug (AED)-related chronic leukopenia [white blood cell (WBC) count < 4,000/microliters] is a dilemma, especially when the AED is effective in controlling seizures. We evaluated the possible mechanisms of leukopenia in 7 patients. Mean WBC count was 3,000/microliters with a mean of 42% polymorphonuclear leukocytes (PMN). The AEDs were carbamazepine (CBZ) alone in 1 patient or CBZ combined with phenytoin (PHT), primidone (PRM), phenobarbital (PB) and/or valproate (VPA) in 5 patients; one patient was receiving PHT only. Bone marrow (BM) aspirates and PMN antibody studies using chemiluminescence were normal. Two liver-spleen scans showed mild relative splenomegaly. After exercise, WBC count (n = 7) increased by 54% (SEM 12%), while the WBC counts in controls (n = 5) increased by 52 +/- 16%. Antinuclear antibodies (Hep-2) were absent in 6 patients and positive (1:160) in 1. PMN adhesion to nylon wool was decreased (54 +/- 10% in patients vs. 80 +/- 5% in controls: n = 13, p < 0.005). Our data, particularly the appropriate WBC response to the stress of exercise, and normal BM examinations suggest that continuation of AED therapy when leukopenia is stable and the percentage of PMN is normal is probably safe. Caution should be used if the absolute PMN count is consistently < 1,000/microliters. BM examinations need not be performed routinely for every patient with neutropenia due to AEDs, especially if the leukopenia fluctuates in the range of 2,000-4,000 cells/microliters.

Detection of antineutrophil autoantibodies by flow cytometry: use of unfixed neutrophils as antigenic targets

Antineutrophil antibodies may be found in the sera of patients with chronic neutropenia as well as in the sera of a variety of patients with neutropenia and associated autoimmune or infectious disorders. We evaluated an immunofluorescent flow cytometric technique for the measurement of antineutrophil antibodies in serum. Sera from patients with suspected immune neutropenia were studied and compared with a group of sera from normal healthy individuals, as well as with sera from patients with rheumatoid arthritis and systemic lupus erythematosus. Of 159 patients with suspected immune neutropenia and a variety of associated clinical disorders, 59 (37%) were found to have evidence for enhanced binding of IgG to normal target neutrophils, interpreted as positive for antineutrophil antibodies. Whereas 0/37 non-neutropenic patients with typical RA had positive results, 51/244 (21%) of sera from nonneutropenic patients with SLE or other collagen vascular disorders showed enhanced IgG binding to neutrophils. Living neutrophils were used to study the effects of cellular activation, and increased antibody binding was observed with certain sera that contained IgG directed against activation-dependent antigens. We found that, under controlled conditions, flow cytometry can be reliably used to detect antineutrophil autoantibodies, with unfixed, living neutrophils as antigenic targets.

IVIG in the treatment of children with acute and chronic idiopathic thrombocytopenic purpura and the autoimmune cytopenias

IVIG has been shown to be useful in the treatment of acute and chronic ITP, immune neutropenia, and in some cases of AIHA. The mechanism of action of IVIG is owing to a number of factors, which include Fc blockade, immune modulation of T- and B-cell number and function, alterations in NK activity, and direct effects on autoantibody binding and production via the antiidiotypic antibody network. Current research efforts are directed toward elucidation of these modalities and determination of their relative importance in treating patients with immune-mediated cytopenias.

Autoimmune neutropenia with anti-neutrophil autoantibody associated with Sjögren's syndrome

A 74-year-old man developed neutropenia in association with Sjögren's syndrome. The peripheral neutrophils in his blood decreased to 210/mm3 (total white blood cell count 2,100/mm3). Bone marrow examination showed an increase in the number of neutrophil precursors. The presence of anti-neutrophil autoantibody (ANAB) in his plasma was determined by an enzyme-linked immunosorbent assay. Prednisolone therapy resulted in an increase in the neutrophil count and a decrease in the ANAB titer. However, when the daily dose of prednisolone was decreased, the neutrophil count gradually decreased, and the ANAB titer increased again. These results suggest that neutropenia in this patient was caused by ANAB, and ANAB could be the result of autoimmune disorders associated with Sjögren's syndrome.

The chemiluminescent response of human monocytes to red cells sensitized with monoclonal anti-Rh(D) antibodies

Luminol-enhanced chemiluminescence (CL) was used to assess the metabolic response of human monocytes to red cells sensitized with known amounts of anti-Rh(D). Monoclonal antibodies were used to facilitate a comparison between the functional activities of IgG1 and IgG3 subclasses. The detection of CL provided a simple, rapid and semi-quantitative means of measuring monocyte response to sensitized red cells (IgG-RBC). Monocyte response to IgG3-RBC was quantitatively greater, more rapid and less susceptible to inhibition by fluid phase IgG than monocyte response to IgG1-RBC. The minimum levels of sensitization required to elicit CL from monocytes were approximately 2500 IgG3 molecules per red cell, or approximately 5000 IgG1 molecules per cell.

Anti-granulocyte opsonic activity in sera from patients with systemic lupus erythematosus

Neutropenia is common in patients with systemic lupus erythematosus (SLE) but mechanisms of cell depletion remain obscure. To investigate the possible autoimmune aetiology of neutropenia in SLE, sera from 31 patients with this disorder were tested for anti-granulocyte activity. Granulocyte-binding immunoglobulins were detected by indirect immunofluorescence, and the ability of patient sera to opsonize granulocytes was determined by measuring the chemiluminescent response of human monocytes to granulocytes sensitized by test sera. Sera from 22 of the 31 patients bound IgG to granulocyte cell membranes and/or to nuclei, but only membrane-binding antibodies opsonized the cells for recognition by monocytes. There was no correlation between neutrophil count and the level of granulocyte-binding IgG as measured by indirect immunofluorescence. In contrast, opsonic activity and neutrophil count were inversely correlated (r = 0.5; P less than 0.05). However, opsonic activity was present in sera from most non-neutropenic patients. In patients with SLE, impaired reticuloendothelial system function may allow sensitized granulocytes to remain in the circulation.