The mechanism of neutropenia in Felty's syndrome

Mathematical modeling of human granulopoiesis: the possible importance of regulated apoptosis

Steady state human granulopoiesis was modeled by a convection-reaction differential equation of the Rubinow type for the bone marrow granulocyte precursors and an ordinary differential equation for the blood granulocytes. Measured values reported from several laboratories were used as sources for the model proliferation, maturation, and mobilization rates. Due to the large variability in the measured input data, four alternative models were constructed initially, each one with a specific combination of proliferation rate and maturation rate. They were all able to produce output values for the bone marrow neutrophil count and turnover rate close to accepted data, but neither of them could reproduce good values for the differential fractions of the neutrophil precursor stages. The model output was especially sensitive to changes in transit time in the mitotic relative to the postmitotic precursor compartments. When the net proliferation rate was modeled to optimize the bone marrow differential fractions according to published data, the total bone marrow neutrophil count would not fit with published data. However, a composite model optimizing differential fractions, bone marrow neutrophil count, and turnover rate yielded plausible output values and a reduced proliferation rate in the myelocyte stage. This result opens for a possibly substantial apoptosis rate at the myelocyte stage in accordance with results from earlier investigators. However, the result was based on a special choice of precursor transit times, taken from the literature. More precise data concerning granulocyte precursor cycle times, transit times, and differential fractions would radically improve the model's ability to clarify the role of apoptosis during granulocyte production and storage.

Successful reversal of neutropenia in Felty's syndrome with recombinant granulocyte colony stimulating factor

We report two patients with Felty's syndrome and chronic skin ulcers treated successfully with recombinant granulocyte colony stimulating factor (GCSF). In both cases granulocytes returned to the normal range within days of starting treatment, and their cutaneous ulcers improved. In one patient granulocytes were maintained at normal levels with a regimen of GCSF 3 micrograms/kg twice weekly for 14 months.

Felty's and pseudo-Felty's syndromes

Felty's syndrome, consisting of rheumatoid arthritis, leukopenia, and splenomegaly, has been recognized as a distinct clinical entity for more than 60 years. Clinical and laboratory manifestations of the condition are reviewed. The major sources of morbidity and mortality remain recurrent local and systemic infections. Immunogenetic analysis shows a strong association with HLA-DR4, in addition to DQ beta 3b and C4B null allele. Potential mechanisms of neutropenia are contrasted, including impaired granulopoiesis and neutrophil-immune complex interactions. Lithium carbonate and splenectomy may have a role in the treatment of fulminant disease. Maintenance therapy should be directed at control of the underlying inflammatory arthropathy. A syndrome of proliferation of large granular lymphocytes and neutropenia, associated with rheumatoid arthritis in 23% to 39% of cases, has been described recently. Cases of "pseudo-Felty's" syndrome are often confused with traditional Felty's syndrome, which has twice the prevalence. The clinical and laboratory distinctions between these two conditions are elaborated.

Effect of corticosteroid treatment on hemopoiesis in vivo and in vitro in a patient with Felty's syndrome

We have studied the CFU-GM and BFU-E in vitro growth in a neutropenic and anemic patient with Felty's syndrome, either before or one and three months after steroid therapy when neutrophils and erythrocytes returned to normal. Both CFU-GM growth and CSA production were found to be low before therapy, and prednisone was shown to raise them to normal levels. The in vitro growth of BFU-E and the production of BPA by T lymphocytes of the patient were significantly lower than normal when studied before therapy. However, the T lymphocytes incubated in vitro with hydrocortisone regained their ability to stimulate the BFU-E growth. After prednisone therapy both BFU-E growth and BPA production by T lymphocytes returned to normal. Possible pathogenetic mechanisms of impaired granulo- and erythropoiesis in Felty's syndrome are discussed. The in vitro study with hydrocortisone can help to identify steroid-sensitive patients.

Reversal of neutropenia with methotrexate treatment in patients with Felty's syndrome. Correlation of response with neutrophil-reactive IgG

We evaluated the clinical and hematologic response to methotrexate (MTX) in 4 women with Felty's syndrome (FS) who had had neutropenia for 1-3 years. Since immune complexes or antineutrophil antibodies are implicated in the pathogenesis of the neutropenia of FS, we also measured both direct and indirect levels of neutrophil-reactive IgG. All 4 patients showed a prompt and dramatic increase in neutrophil counts within 1-2 months of starting MTX therapy. In 3 patients, the symptoms of arthritis also improved; in the fourth patient, arthritis worsened. Recurring infections ceased in 3 patients. Neutrophil-reactive IgG levels, which were elevated in all patients prior to treatment, decreased toward normal while the patients were receiving MTX therapy. We conclude that MTX is effective in treating the neutropenia of FS, in part by lowering neutrophil-reactive IgG.

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.

The spleen in Felty's syndrome: a histological, morphometrical, and immunohistochemical study

A histological study employing morphometrical and immunohistochemical methods was performed in 3 spleens removed because of Felty's syndrome (FS). A comparison was made with control spleens and with spleens removed from patients with idiopathic thrombocytopenic purpura (ITP) or autoimmune hemolytic anemia (AIHA). In FS, the spleen is enlarged, mainly due to expansion of the red pulp. The sinuses are enlarged, too, and contain many macrophages. 2 of our specimens showed many hyperplastic germinal centers; the 3rd contained no germinal centers. Only in the former cases did splenectomy lead to an increase in the number of circulating granulocytes. Immunohistologically, FS spleens differed from the control, the ITP, and the AIHA spleens. The results have provided further evidence indicating that the pathogenesis of granulocytopenia in FS differs from that of autoimmune hematocytopenias, and have given rise to the hypothesis that, in FS, the spleen is the site of interaction between immune complexes and granulocytes.

Immune complexes and the pathogenesis of neutropenia in Felty's syndrome

The effect of the injection of serum from patients with rheumatoid arthritis (RA) and Felty's syndrome (FS) into mice on the number of circulating polymorphonuclear cells (PMN) was studied. The number of circulating PMN dropped to 61% (range 34-98%) of the initial counts after the injection of FS serum. This phenomenon was observed less frequently after injection of RA serum. In contrast, injection of serum from healthy controls always resulted in an immediate increase in the number of circulating PMN. No decrease in PMN counts was found after injection of FS sera pretreated with polyethylene glycol to precipitate immune complexes (IC). Gel filtration of FS sera on Sepharose 4B showed that the effect on the PMN counts in mice did not coincide with the 7S peak but occurred only in fractions containing larger material. Serum fractions from FS patients that contained IC were more active in producing neutropenia than the corresponding fractions from patients with RA. Microscopic and immunohistochemical examination of the organs from mice injected with FS serum showed sequestration of PMN and deposition of human IgG, IgA, and IgM in the vascular bed of the lungs. These results indicate that the interaction between PMN and IC of patients with FS leads to sequestration of PMN in mice and suggests that this interaction in humans may have a role in the pathogenesis of FS.

Chronic idiopathic and secondary neutropenia: clinical and serological investigations

Clinical data on 49 patients with chronic idiopathic neutropenia (CIN) and 42 patients with neutropenia secondary to a well-defined immunological disorder (SN) were collected and related to serological parameters. In 47% of the patients with CIN and 53% of those with SN, a positive direct immunofluorescence test was obtained with granulocytes from the patients. In the sera from the patients in the two groups, antibodies against donor granulocytes were detected by the indirect immunofluorescence test, the leucoagglutination test and/or the granulocytotoxicity test in 15%, 19% and 15%, respectively. The results of the above tests could not be correlated with any clinical or haematological parameter. Immune complexes in the serum were detected by the 125I-Clq-binding test in 29% of patients with CIN and in 58% of those with SN. The presence of serum immune complexes correlated well with the existence of a low neutrophil count, but not with the presence of recurrent infections, with bone-marrow abnormalities, or with positive reactions in other serological tests. The sera of eight out of 14 patients with CIN and seven out of 12 patients with SN had inhibitory activity for myeloid colony formation in vitro (CFU-GM). This CFU-GM inhibitory activity was correlated with the presence of recurrent infections and with hypoplasia of the myeloid compartment of the bone marrow, but not with positive reactions in other tests. We conclude that the 125I-Clq-binding test probably detects circulating immune complexes that induce a shift neutropenia, whereas serum activity inhibitory for CFU-GM possibly relates to clinically more serious forms of neutropenia. The significance of neutrophil-bound Ig and granulocyte-reactive antibodies in the serum is not clear.

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.

Felty syndrome: autoimmune neutropenia or immune-complex-mediated disease?

Immunofluorescence on polymorphonuclear cells (PMN) of patients with Felty syndrome (FS) revealed increased amounts of IgG, IgA, and IgM bound to the PMN surface compared with PMN of patients with rheumatoid arthritis alone. A positive correlation was found between the score for surface-bound immunoglobulins on FS-PMN and the results of the Clq binding assay in FS sera. After preincubation with sera from 20 patients with FS, immunofluorescence on PMN from healthy controls (HC) showed that these cells had bound IgG, IgA, and IgM. However F(ab')2 fragments of IgG from FS sera did not bind to PMN, although the antigen-binding reactivity of the F(ab')2 fragments was maintained as shown by control experiments. Immunoglobulins eluted from FS-PMN failed to bind to HC-PMN, whereas the corresponding IgG of patients with autoimmune neutropenia was bound. Gel filtration of FS sera on Sepharose 4B showed that the binding of IgG in FS sera to PMN did not coincide with the 7S peak but occurred mainly in fractions containing larger material. No binding of IgA and IgM to HC-PMN was found after incubation with FS sera pretreated with polyethylene glycol (PEG) to precipitate immune complexes. These results indicate that in sera of patients with FS the PMN-binding reactivity of IgG, IgA, and IgM is due to the binding of immune complexes containing these immunoglobulins and not to presence of autoantibodies directed to antigens on the neutrophil surface.

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.

Felty's syndrome associated with high levels of IgA rheumatoid factor

A 64-year-old woman with rheumatoid arthritis developed Felty's syndrome. Her serum contained large amounts of IgA rheumatoid factor (RF) but insignificant levels of IgM-RF and IgG-RF. It is postulated that the high levels of IgA-RF may have contributed to the neutropenia.

Heterogeneity of bone marrow-directed immune mechanisms in the pathogenesis of neutropenia of Felty's syndrome

Twenty-seven patients with Felty's syndrome were studied by the colony forming unit in culture (CFU-C) assay for possible immune mechanisms within the bone marrow compartment that could contribute to the neutropenia. Depletion of bone marrow suppressor T cells resulted in normal CFU-C numbers in 7 patients. In 5 patients serum antiprecursor cell activity was detected. Blood monocytes failed to generate colony stimulating factor in 5 patients. Bone marrow-directed immune mechanisms are heterogeneous and could play a role in the pathogenesis of neutropenia in some patients with Felty's syndrome.

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.

Influence of the spleen on the distribution of blood neutrophils. Quantitative studies in the rat

The influence of the spleen on the distribution of blood neutrophils was studied in rats with varying spleen sizes following transfusion of isologous 3H-dT-labelled neutrophils. The weight of the spleen correlated with the splenic neutrophil pool (r = 0.87, P less than 0.01). Alterations in spleen size did not significantly change the total blood neutrophil pool, but with increasing splenomegaly circulating and marginal neutrophils were shifted into the splenic pool. With massive splenomegaly, up to 50% of the total blood neutrophils were trapped in the spleen. These findings suggest splenic pooling of neutrophils and a shift of circulating and marginal neutrophils into the spleen proportionate to the splenic tissue present.

Increased endothelial cell adherence, aggregation, and superoxide generation by neutrophils incubated in systemic lupus erythematosus and Felty's syndrome sera

The ability of sera from patients with systemic lupus erythematosus (SLE) and Felty's syndrome to induce increased adhesiveness of normal human neutrophils (PMN) was investigated. PMN from normal healthy donors were incubated in sera from 19 patients with active SLE, 12 with inactive SLE, 20 with Felty's, 24 with rheumatoid arthritis, and 34 normal persons. After incubation, the degree of adherence of the PMN to human endothelial cells in culture, their aggregation, and superoxide (O2-) generation were determined. Sera from patients with both active SLE and Felty's syndrome induced significantly increased PMN adherence to endothelial cells and PMN aggregation in vitro, compared with normal sera. This increased adherence to endothelial cells was maintained after heat treatment (56 degrees C for 30 minutes) of the sera. In O2- generation experiments, sera from patients with active SLE induced significantly increased O2- release from normal PMN using both fresh and heat-treated sera. Sera from Felty's patients demonstrated the same effect with heat-treated sera but not ith fresh sera. When sera from patients with active SLE and Felty's syndrome were used, all three parameters correlated significantly with each other in individual patients. In contrast, sera from the 12 patients with inactive SLE and 24 rheumatoid arthritis patients without Felty's failed to induce significant differences in the three parameters studied when compared with 34 normal controls. Fractionation of 3 SLE sera and 1 Felty's serum on Sephadex G-200 demonstrated that the adherence enhancing factor was present in both IgG and IgG-excluded fractions. The observed increased adhesiveness of PMN induced by SLE and Felty's sera may, at least in part, contribute to the neutropenia which is common in these diseases. Increased O2- release associated with PMN adherence may contribute to endothelial cell damage and vascular injury, which is also a common manifestation of these diseases.

Long-term outcome in Felty's syndrome

Felty's syndrome has again been shown to be a severe form of systemic rheumatoid disease characterised by severe joint involvement, many extra-articular features, and a high incidence of infection. In addition we have shown that splenectomy was not protective for infections and in fact may on occasion contributed to infection. Furthermore, although most patients had an increase in white blood cell count after splenectomy, 50% of patients without splenectomy showed a similar increase in white blood cell counts at follow-up. Mortality in Felty's syndrome was high, with infection being the main cause of death.

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/microliter. 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.

111Indium-labelled white blood cells in the diagnosis of Felty's syndrome

The use of isotope scanning of the spleen in conjunction with 51Cr-labelled red blood cells has become an established technique in the evaluation of patients with hypersplenism. As far as we are aware the similar technique using labelled white blood cells to demonstrate splenic sequestration in a neutropenic patient has not been described. We report a case where this technique proved valuable in confirming the diagnosis and in predicting a favourable response to splenectomy.

Polymorphonuclear cell function in rheumatoid arthritis and in Felty's syndrome

Tests for polymorphonuclear cell (PMN) chemotaxis, adherence, and electrophoretic mobility (EPM) were carried out on blood PMN isolated from 27 normal subjects, 16 patients with uncomplicated rheumatoid arthritis (RA), and 9 patients with Felty's syndrome. Chemotaxis was measured by a modification of the Boyden chamber technique, adherence by retention of cells on nylon fibre columns, and EPM in a cylindrical electrophoretic assembly. There was no significant difference between the chemotactic migration of normal and rheumatoid PMN as assessed by the leading front measurement. However, PMN from patients with Felty's syndrome showed significantly reduced chemotaxis (P less than 0.001). Computerised image analysis showed this impaired migration to be due to an overall reduction in cell motility rather than loss of a subset cells. Activated serum from patients with RA and Felty's syndrome were as good chemoattractants as activated pooled AB serum. There was no significant difference in the adhesiveness of PMN from normal persons and rheumatoid patients, though PMN from patients with Felty's syndrome did show a trend to lower adhesiveness. Both RA and Felty's syndrome patients had an increase in the proportion of PMN of lower surface charge than controls. Direct correlations were observed between cells of high surface charge and nonadhesiveness.

Neutrophil kinetics in Felty's syndrome

In 19 patients with Felty's syndrome, marrow production of neutrophils and neutrophil distribution were studied. Despite accelerated marrow release and disappearance of mature blood neutrophils, there was little or no increase in the marrow mitotic pool or in vitro progenitor cells. Only two patients had an increase in marrow neutrophils and precursors. Antineutrophil antibody was detected in seven of nine patients studied. Neither abnormal margination of blood neutrophils nor impaired marrow release of cells was detected. Skin exudate cellularity tended to correspond to prior history of infections, asymptomatic patients having more cellular exudates. Sustained neutrophil increments were observed in six of 10 patients following splenectomy, but in no patient did neutrophil kinetics return completely to normal. Three of four patients who failed to respond to splenectomy with sustained increments in blood neutrophils had a reduced mass of marrow neutrophils and neutrophil precursors when studied prior to splenectomy. No diminution in neutropenia was observed in any of five patients treated with lithium carbonate. This study indicates that multiple factors are involved in the pathogenesis of neutropenia in Felty's syndrome. In particular, neutropenia was associated with inadequate marrow granulocytopoiesis. The severity of the impairment, as determined by the mass of marrow neutrophils and precursor cells, may be useful in predicting response to splenectomy.

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.

Neutrophil marrow profiles in patients with rheumatoid arthritis and neutropenia

Neutrophil marrow cellularity was determined in 14 neutropenic patients with rheumatoid arthritis (RA) from measurements of neutrophil-normoblast ratios in marrow biopsies and ferrokinetic estimates of marrow normoblasts. A marrow profile was developed for each patient comprising the numbers of promyelocytes and myelocytes, of metamyelocytes and bands, and of segmented neutrophils in whole marrow. In each case a maturation ratio was calculated by dividing the number of metamyelocytes and bands by the number of promyelocytes and myelocytes. The physiologic marrow response to loss of neutrophils from circulation was assumed to be an increase in promyelocytes and myelocytes due to proliferation and influx, a reduction in segmented cells due to early release, and a normal maturation ratio. The results were interpreted in the light of the 95% confidence limits for data previously obtained from 13 normal subjects: in patients with neutropenia reduced or basal numbers of promyelocytes and myelocytes were interpreted as absence of the anticipated proliferative response; increased numbers of marrow segmented cells were attributed to failure of release; a low maturation ratio was assessed to reflect intramedullary cell loss. The pattern in two patients with Felty's syndrome was consistent with a physiological response to neutrophil destruction. The other 12 patients had neutrophil marrow abnormalities. Seven patients with Felty's syndrome and four patients without splenomegaly had absolute or relative hypoplasia of neutrophil marrow or low maturation ratios. One patient with a normal spleen size had an increased number of marrow segmented cells yet failed to mobilize cells normally in response to dialysis coil-activation of C3. Abnormalities of neutrophil marrow may contribute to neutropenia in RA irrespective of the presence of splenomegaly. Recognition of neutrophil marrow abnormalities in these patients may be of value in prognosis and management.

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.

Increased C1q binding immune complexes in Felty's syndrome: comparison with uncomplicated rheumatoid arthritis

Sera from patients with Felty's syndrome (FS) and rheumatoid arthritis (RA) were examined for the presence of circulating immune complexes (IC) by using the 125I-C1q binding and monoclonal rheumatoid factor (mRF) techniques. Of 15 patients with FS, 9 (60%) had high 125I-C1q binding as compared to 3 of 26 RA patients (12%). The average C1q binding was significantly higher in the FS patients than in the RA patients without FS. C1q binding in both FS and RA patients was significantly higher than a group of 90 normal controls. In addition, serum C4 levels were significantly lower in the FS patients than in the RA patients. In contrast to these findings, IC levels in FS and RA patients were very similar when measured by the mRF technique. These studies indicate that FS patients have higher levels of complement-fixing IC in their sera than RA patients without FS. These findings raise the possibility that the complement-fixing IC found in these patients may play a role in the pathogenesis of neutropenia of FS.

Splenic function: normal, too much and too little

This review is concerned with normal splenic function, mechanisms and consequences of splenomegaly, hypersplenism, the medical indications for splenectomy and the various aspects of hyposplenism. The potential probelm of lethal septicemia in hyposplenic or asplenic patients is also considered.

Comparison of the presence of immune complexes in Felty's syndrome and rheumatoid arthritis

Evidence has been found to document the presence of circulating immune complexes in all patients with Felty's syndrome. The sera of all 12 patients studied showed intermediate complexes by analytical ultracentrifugation. The sera of 9 of 12 patients (75%) showed precipitin lines upon immunodiffusion against IgM rheumatoid factor. Both findings were statistically increased above those in a matched group of patients with classic rheumatoid arthritis. The presence of circulating immune complexes in the sera of the Felty patients was consistent with the observation that large inclusions containing IgG, IgM, and complement were phagocytized by normal polymorphonuclear cells when incubated with sera of Felty patients. Normal polymorphonuclear cells phagocytosed inclusions from 77% of Felty sera, compared with 27% classic rheumatoid arthritis sera. It is suggested that the uptake of immune complexes by polymorphonuclear cells plays a role in the neutropenia of Felty's syndrome.

Immune suppression of hematopoiesis

Recent evidence suggests that immune mechanisms can injure proliferating hematopoietic precursor cells in the bone marrow. These may involve either humoral antibody or cell-mediated cytotoxic mechanisms. Immune injury can result in a variety of bone marrow failure syndromes. Immunologically induced abnormalities or blood cell production may be restricted to a single series, such as erythrocyte or granulocyte precursors, or may involve several hematopoietic lines; clinical manifestations reflect the cell line or lines that are injured. Immune suppression of hematopoiesis has now been described in pure red cell aplasia, immune panleukopenia, systemic lupus erythematosus, atypical cases of aplastic anemia and miscellaneous other hematologic diseases.

The measurement of granulocyte kinetics

Studies using 3H-TdR, DF32P or 51Cr have all contributed important information concerning neutrophil kinetics in normal and abnormal conditions. Recent evidence, however, suggests that DF32P underestimates, and 51Cr overestimates, the blood neutrophil T1/2 and that both isotopes overestimate the TBNP, compared with 3H-TdR-derived data. The differences are quantitative and not qualitative, and the principles of blood neutrophil kinetics defined by DF32P studies are still valid. 3H-TdR studies are impractical for general use, and clinical measurement of neutrophil kinetics will have to continue to rely on the use of either DF32P or 51Cr. Comparison of abnormal findings with normal values obtained using the same isotope is probably valid for either technique. Changes in neutrophil kinetics leading to a neutrophil leucocytosis in different situations are fairly predictable from published data. In neutropenias, however, kinetic studies might be needed to delineate the relative contributions of under-production, shortened survival and excessive margination in the individual patient.

Cryoimmunoglobulinemia in Felty's syndrome

Seven of 9 patients with Felty's syndrome exhibited cryoglobulins in greater amounts than found in uncomplicated RA but similar to amounts found in RA with vasculitis. Antinuclear antibodies were found in high titer in the sera and cryoglobulins of Felty's patients; when compared to SLE patients, whose sera and cryoglobulins also contained antinuclear factors, an antinuclear antibody reacting with nuclei of polymorphonuclear granulocytes appeared to be selectively concentrated in the cryoglobulins of some Felty's patients.