The neutropenia of Felty's syndrome

Lack of evidence for the presence of neutrophil autoantibodies in the serum of patients with Felty's syndrome

Sera of 22 patients with Felty's syndrome and 14 patients with rheumatoid arthritis were tested in assays routinely used for the detection of neutrophil antibodies (i.e. immunofluorescence, agglutination and cytotoxicity tests) as well as in the antibody-dependent lymphocyte-mediated granulocytotoxicity test. One or more of the routinely used assays were positive in a high percentage of the sera (77% and 64%, respectively). The antibody-dependent lymphocyte-mediated granulocytotoxicity test was only positive with sera of three patients with Felty's syndrome. Positive results in the immunofluorescence and agglutination tests could be attributed to the presence of immune complexes in the sera, whereas positive antibody-dependent lymphocyte-mediated granulocytotoxicity tests were probably due to the presence of HLA alloantibodies. It is concluded that serological tests routinely used for the detection of neutrophil autoantibodies should be interpreted with caution in patients with Felty's syndrome. Our results also indicate that the neutropenia in Felty's syndrome is rarely, if ever, due to neutrophil-specific autoantibodies.

Radiolabeled blood cells: techniques and applications

During the past few years, the clinical and experimental applications of autologous blood cells labeled with gamma-emitting radionuclides, i.e., technetium-99m (Tc-99m) and indium-111 (In-111) have continued to grow rapidly. Investigations have centered around developing techniques that would label blood cells efficiently without alteration of cell viability and their pathophysiologic integrity. Experimental and clinical applications have been aimed at the studies of in vivo cell kinetics and detecting abnormal lesions by external imaging. These will be discussed in detail together with their advantages and disadvantages, and the future directions will be outlined.

Labeled cells in the investigation of hematologic disorders

Radiolabeling techniques for white cells, platelets, and erythrocytes are reviewed. The early studies using diisopropylfluoro-32P contributed to an understanding of the production and circulation of the blood elements, and 51Cr proved useful in localizing sites of cell migration or destruction. 111In-oxine has further improved the understanding of blood cell organ sequestration, and permitted combined kinetic and organ imaging studies. Radionuclide labels have been essential for the elucidation of various hematologic disorders, such as the neutropenias, thrombocytopenias, anemias, and polycythemia. Many new treatments, including monoclonal antibodies, have been evaluated with radionuclides.

Antibodies reactive with surface membranes of cellular elements in the blood

Autoreactive antibodies or immune complexes may accelerate clearance of mature erythrocytes, leukocytes, and platelets from the circulation in patients with rheumatologic and immunologic disorders. The most compelling evidence for immune injury to hematopoietic cells exists in patients with systemic lupus erythematosus and patients with Felty's syndrome and its variants. These disorders may also cause tissue inflammation, which in turn commonly results in underproduction of erythrocytes and development of thrombocytosis. However, recent evidence indicates that underproduction of hematopoietic cells may also result from immune injury to cellular elements in the bone marrow. In many laboratories, sensitive techniques are now clinically available for the detection of cell-associated immunoglobulin and complement. These assays have helped confirm the role of antibody in the pathogenesis of autoimmune hemolytic anemia and idiopathic thrombocytopenic purpura. However, recent data indicate that there is probably a continuum between the amount of immunoglobulin and complement found on normal cells and that found in a variety of disease states. In several of these disorders, additional evidence will be required to establish that the increase in cell-bound immunoglobulin leads to a decrease in the life-span of the cell. In order to provide significant help to the clinician managing an individual patient, these serologic tests must be capable of identifying the portion of the cell-associated protein actually involved in the destructive process. The availability of monoclonal reagents capable of identifying restricted regions on cell-bound immunoglobulin may help identify molecules bound specifically as antibody and may help identify the antigens involved in autoimmune disorders.

Phagocytosis of neutrophils by marrow macrophages in childhood chronic benign neutropenia

Chronic benign neutropenia of childhood is a heterogeneous disorder. This study describes two severely neutropenic children with a benign clinical course and the unique bone marrow finding of macrophage engulfment of band and segmented neutrophils. Phagocytic vacuoles in the majority of macrophages contained neutrophils in various stages of digestion at both the light and electron microscope level (with as many as four neutrophils observed in single macrophages). Ultrastructural studies demonstrated that the neutrophils were morphologically normal, and apparently viable at the time of phagocytosis. This type of neutrophil phagocytosis was not observed in five other consecutively studied children with CBN. All of these children with CBN had ultrastructurally normal neutrophils, lacked demonstrable antineutrophil antibodies or serum inhibitors to in vitro myelopoiesis, and had normal colony-forming cells and colony-stimulating activity in vitro. Thus despite many similar clinical and laboratory features in children with CBN, only a unique subgroup of these patients demonstrates abnormal neutrophil-macrophage interaction.

Cell mediated autoimmune granulocytopenia in a case of Felty's syndrome

A variety of mechanisms have been demonstrated or suggested to explain the neutropenia that accompanies Felty's syndrome. This case report presents with Felty's syndrome with recurrent infections with initially had a clinical response to splenectomy. Eleven years later profound neutropenia recurred. In-vitro evidence for cell mediated autosensitisation of peripheral blood lymphocytes to autologous bone marrow cells was found. The cellular abnormalities improved after high-dose corticosteroids but not lithium. However, there did not appear to be a reduction in the incidence of clinical infections. The finding suggests that granulocytopenia in some patients with Felty's syndrome may be an autoimmune phenomenon.

The rarity of Felty's syndrome in blacks

Evidence is presented that Felty's syndrome (FS) is rare among black patients with rheumatoid arthritis (RA). All of 12 patients with FS seen at Parkland Memorial Hospital, Dallas, Texas betwen 1964 and 1978 were white. During this period 52% of patients admitted to the Parkland medical service were black and 31% of patients dischargd with a diagnosis of RA were black. The number of expected black cases of FS on the basis of the racial distribution of hospitalized patients with RA was 3.7 (P is less than 0.02 when the zero incidence in blacks was compared with the expected incidence). All 7 cases of FS observed at Charity Hospital, New Orleans, Louisiana between 1968 and 1978 were also white. During this period, 65% of patients discharged with a diagnosis of RA were black, and the number of expected black cases of FS was 4.5 (P is less than 0.001). These findings suggest a genetic basis for the development of leukopenia and splenomegaly in RA patients.