Platelet antibody levels do not correlate with response to therapy in idiopathic thrombocytopenic purpura

Splenectomy for adult patients with idiopathic thrombocytopenic purpura: a systematic review to assess long-term platelet count responses, prediction of response, and surgical complications

Splenectomy has been a standard treatment for adult patients with idiopathic thrombocytopenic purpura (ITP) for more than 50 years. However, the durability of responses, the ability to predict who will respond, and the frequency of surgical complications with splenectomy all remain uncertain. To better interpret current knowledge we systematically identified and reviewed all 135 case series, 1966 to 2004, that described 15 or more consecutive patients who had splenectomy for ITP and that had data for 1 of these 3 outcomes. Complete response was defined as a normal platelet count following splenectomy and for the duration of follow-up with no additional treatment. Forty-seven case series reported complete response in 1731 (66%) of 2623 adult patients with follow-up for 1 to 153 months; complete response rates did not correlate with duration of follow-up (r = -0.103, P = .49). None of 12 preoperative characteristics that have been reported consistently predicted response to splenectomy. Mortality was 1.0% (48 of 4955 patients) with laparotomy and 0.2% (3 of 1301 patients) with laparoscopy. Complication rates were 12.9% (318 of 2465) with laparotomy and 9.6% (88 of 921 patients) with laparoscopic splenectomy. Although the risk of surgery is an important consideration, splenectomy provides a high frequency of durable responses for adult patients with ITP. (Blood. 2004; 104:2623-2634)

Management of immune thrombocytopenic purpura in adults

Primary immune thrombocytopenic purpura (ITP), also referred to as idiopathic thrombocytopenic purpura, is an organ-specific autoimmune disorder in which antibody-coated or immune complex-coated platelets are destroyed prematurely by the reticuloendothelial system, resulting in peripheral blood thrombocytopenia. The disease is heterogeneous with regard to its severity and clinical course and is unpredictable in its response to therapy. Although the basic underlying pathophysiology of ITP has been known for more than 50 years, current treatment guidelines are based on expert opinion rather than on evidence because of a lack of high-quality clinical trials and research. The only patients for whom treatment is clearly required are those with severe bleeding and/or extremely low platelet counts (< 10 x 10(9)/L). Treatment of patients with ITP refractory to corticosteroids and splenectomy requires careful evaluation of disease severity, patient characteristics related to risk of bleeding, and adverse effects associated with treatment. Clinical trials with numerous new agents are under way, which we hope will add more effective and targeted strategies to our therapeutic armamentarium. We describe a logical and structured approach to the clinical management of ITP in adults, based on a literature review and our personal experience.

Magnetic resonance imaging of reticulo-endothelial system in patients with idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) is characterized by accelerated platelet destruction in the reticulo-endothelial system (RES). We performed magnetic resonance imaging (MRI) to estimate the degree of activated RES. MRI was performed with a Gyroscan S-15 (1.5 tesla) in 7 healthy volunteers and 22 patients with ITP. The 22 patients included 19 who were at initial diagnosis or were nonresponders to the therapy (non-DX group), and 3 who were responders. For the non-DX group, the T1 relaxation time of the spleen was initially significantly shorter than for healthy volunteers, but normalized after responding to the therapy. The initially shorter T1 values of the spleen for ITP patients correlated with a low platelet count (P < 0.05). This condition may indicate foam cells or fatty components due to platelet destruction. There was no significant relationship between the sequestration in (111)In-scan and T1 values of the liver or spleen. However, MRI is a noninvasive method, and it may be a clinically useful tool in the evaluation of RES in patients with ITP.

Long-term observation of 208 adults with chronic idiopathic thrombocytopenic purpura

PURPOSE

To define response to therapy and ultimate outcome of adults with idiopathic thrombocytopenic purpura (ITP).

PATIENTS AND METHODS

We retrospectively analyzed patients with ITP diagnosed between 1978 and 1988, and reexamined them between June 1992 and March 1993. Data from 208 cases were collected. Median patient age was 44 years (range 14 to 78) at the time of diagnosis, and 51 years (range 19 to 86) at reexamination. Length of follow-up ranged from 48 to 151 months (median 92) and was longer than 10 years in 26 patients (12.5%). Reexamination included a careful interview, physical examination, complete blood count, screening for HIV infection, determination of platelet-bound IgG, and, in persistently thrombocytopenic patients, autoimmunity markers and routine laboratory investigations.

RESULTS

A total of 121 patients with fewer than 50 x 10(9) platelets per liter received an initial treatment with prednisone (PDN) at a dosage of 1 mg/kg of body weight for 1 month. Refractory or relapsed cases underwent splenectomy and/or other therapeutic modalities. In 87 patients with greater than 50 x 10(9) platelets per liter, no therapy was scheduled. An initial complete response to PDN was observed in 38.8% cases. A sustained complete remission (CR) lasting more than 6 months with no maintenance therapy was attained in 18.7%. At the time of last follow-up only 11 of these patients remained in CR. Sixty-three patients underwent splenectomy. Forty-seven (74.6%) had a CR, with 41 achieving a prolonged recovery (> 6 months). Twelve other cases attained a sustained partial remission. Long-lasting recoveries were observed in 7 other cases following alternative treatments. Spontaneous remissions occurred in 8 of 87 untreated cases after observation periods of 6 months or more. Eleven deaths were recorded (6 women and 5 men, median age 73), but only 5 were attributable to thrombocytopenia. At last control, 43 patients were in complete remission and free from therapy, and 52 were still on therapy. Four thrombocytopenic patients had laboratory features and a clinical history consistent with an autoimmune disease.

CONCLUSIONS

This analysis of ITP in adults suggests that splenectomy remains the most effective treatment. The majority of patients who undergo splenectomy can have a CR for many years, while only a minority of those who do not have this therapeutic modality or fail it are likely to attain similar results. The long-term prognosis of ITP is benign even in refractory cases. Spontaneous remissions can be observed in a significant percentage of untreated patients (about 9%). The development of overt autoimmune diseases is relatively uncommon. Particular attention should be given to the management of ITP in the elderly, where bleeding episodes of the central nervous system tend to occur more frequently.

Successful alpha-interferon therapy in a child with chronic refractory idiopathic thrombocytopenic purpura: a case report

We treated a sixteen month old male with chronic refractory idiopathic thrombocytopenic purpura (ITP) in whom alpha-interferon (IFN) therapy was effective. He developed ITP which did not respond to various treatments. Six months after admission, we began to treat him with IFN. The patient's platelet count rapidly responded to the therapy and rose above normal range. Serum levels of platelet associated immunoglobulin G (PA-IgG) showed a tendency to decrease with the administration of IFN. After stopping the IFN therapy for a duration of 3 months, the platelet count remained normal. No serious adverse side effects, except transient fever, were observed. From the experience of this case we propose that IFN is one of the therapeutic options for treatment of refractory ITP not only in adults but also in children.

Lack of useful clinical predictors of response to splenectomy in patients with chronic idiopathic thrombocytopenic purpura

We set out to identify clinical or analytical variables that might predict the response to splenectomy in patients with chronic idiopathic thrombocytopenic purpura (ITP). We retrospectively examined 138 mostly adult patients with chronic ITP, treated with splenectomy. Information was compiled from five Public Health Hospitals from a questionnaire and chart review. Sixty-one potentially prognostic variables were analysed by univariate and multivariate statistical methods. After multivariate analysis, age (relative risk = 1.02; CI 1-1.03) and a severity of the bleeding diathesis (relative risk = 1.6; CI 1.13-2.22) were independent prognostic factors for a sustained response to splenectomy. An independent analysis of the postsplenectomy counts showed that an early (days 1-3) thrombocyte count exceeding 156 x 10(9)/l cells increases the likelihood of a permanent unmaintained response. Our data indicate that the response to splenectomy in patients with chronic ITP cannot be adequately predicted on the basis of pre-splenectomy clinical or analytical variables.

Splenectomy for primary and recurrent immune thrombocytopenic purpura (ITP). Current criteria for patient selection and results

Of 565 patients with thrombocytopenia admitted to Duke University Hospital between 1975 and 1985, 100 had splenectomy. Ninety-eight patients had failed chronic immunosuppressive therapy and three patients had acute intracranial bleeding or total absence of platelets in the peripheral blood smear, and had urgent splenectomy. At primary splenectomy, accessory spleens were identified and resected in 18% of patients. There was no operative mortality. Fifty-eight patients had an excellent response to splenectomy and their steroids were tapered off within 3 weeks. Thirteen patients had a poor response to primary splenectomy of whom eight remitted spontaneously and five required accessory splenectomy resulting in complete remission in three patients. Twenty-nine patients were considered nonresponders, 25 of whom had radionuclide scanning for accessory spleens. Seven of these patients had accessory spleens identified but only four consented to accessory splenectomy. In three of the four patients, a complete remission was achieved. Neither platelet antibody titers nor measurements of platelet survival or turnover predicted platelet response to splenectomy. However, immune thrombocytopenic purpura (ITP) in older patients was significantly less likely to respond to splenectomy. These data support continuing use of splenectomy in selected patients with ITP and an aggressive search for accessory spleens in patients who relapse since they are easily localized at operation by hand-held isotope detector probe.

Effect of danazol in immune thrombocytopenic purpura

Danazol and vinblastine are effective in many patients with chronic immune thrombocytopenic purpura (ITP). To evaluate the mechanism of action of these drugs, we studied six consecutive patients with chronic ITP treated with danazol and one treated with vinblastine. All the patients responded clinically without a notable change in the level of platelet-associated IgG. Instead, the clinical response to therapy was associated with a decrease in the number of monocyte binding sites for monomeric IgG (Fc receptors). In one patient, clinical relapse was associated with a spontaneous 2.7-fold increase in the number of monocyte Fc (IgG) receptors, without a change in the level of platelet-associated immunoglobulin. A decrease in the number of monocyte Fc (IgG) receptors following vinblastine infusion was associated with a clinical remission. We conclude that the clinical course of ITP may be influenced by the expression of monocyte or macrophage Fc (IgG) receptors. Danazol and vinblastine may mediate their clinical effect, at least in part, by influencing the number of available Fc (IgG) receptors on phagocytic cells.

[Detection of platelet antibodies in idiopathic thrombopenic purpura]

The authors report the results of Dixon's assay modified by Follea in 24 cases of idiopathic thrombocytopenic purpura. The level of immunoglobulin G bound to platelet membrane was increased in 91 p. 100 of patients in the acute phase of the disease. An inverse correlation was demonstrated between platelet-bound antibody levels and platelet count as well as platelet survival. In all cases of refractory idiopathic thrombocytopenic purpura, the assay was positive and the mean level was higher. When the platelet count improved after prednisone therapy or after splenectomy, the level decreased. Platelet antibody determination seems to be useful for predicting the course of the disease. Patients with normal immunoglobulin G bound to platelet might have only C3, IgM or IgA. Dixon's assay is not specific to idiopathic thrombopenic purpura, since it is positive in other types of thrombocytopenia, but immunoglobulin G bound to platelet probably represents specific antiplatelet antibodies.

Complement-dependent cytotoxic factor to megakaryocyte progenitors in sera from patients with idiopathic thrombocytopenic purpura

The influence of sera from patients with idiopathic thrombocytopenic purpura (ITP) was examined on colony formation from megakaryocyte (M) progenitors. Though incubation of marrow cells in Iscove's modified Dulbecco's medium (IMDM) containing 50% sera from several ITP patients stimulated M-colony formation in 8 of 13 cases, incubation in the sera from the patients and in baby rabbit serum as a source of complement significantly suppressed the colony formation. Experiments showed that sera of immunoglobulin G from ITP patients had significant complement-dependent cytotoxicity to M-progenitors in normal marrow cells or in the marrow cells from corresponding patients, but not to CFU-e, BFU-e or CFU-gm. Cytospin preparations of individually collected M-colonies from marrow cells treated with ITP patients' sera and complement revealed a reduction of megakaryocyte colonies containing cells of multilineages. These results indicate that autoantibodies detected in ITP patients can bind not only to platelets and megakaryocytes, but may also bind to M-progenitors.

Platelet antibodies of the IgM class in immune thrombocytopenic purpura

The clinical course and response to therapy of patients with immune thrombocytopenic purpura (ITP) are not completely determined by the level of IgG present on the platelet surface. It is possible that antibodies of other immunoglobulin classes also play a role in platelet destruction in some of these patients. Therefore, we studied 175 patients with ITP for the presence of IgM anti-platelet antibodies using radiolabeled polyclonal or monoclonal anti-IgM. We observed that 57% of patients with clinical ITP had increased levels of IgM on their platelets, compared with normal controls and patients with thrombocytopenia who did not have ITP (less than 10%), (P less than 0.01). We obtained similar results using either radiolabeled polyclonal or monoclonal anti-IgM, reagents whose integrity was first characterized using erythrocytes coated with defined amounts of IgM antibody. Among patients with increased platelet-IgM there was a significant correlation both with the presence of increased platelet-C3 as well as the amount of platelet-C3 (P less than 0.01, r = 0.53). We demonstrated the presence of warm-reacting IgM anti-platelet antibodies in the plasma of two of these patients who were further studied. The isolated IgM fraction from these two plasmas was able to activate complement and place 3H-C3 on normal platelets. These studies demonstrate the presence of warm-reacting IgM anti-platelet antibodies in some patients with ITP. They suggest that the binding of complement to platelets by IgM antibodies may initiate platelet clearance as well as enhance the effect of IgG antibodies in ITP.

Detection of platelet-associated IgG in chronic immune thrombocytopenic purpura using antibody-coated polyacrylamide beads

Platelet-associated IgG (PAIgG) was detected by means of anti-human IgG coated polyacrylamide beads ("Immunobeads") technique in 32 patients with chronic ITP. Both a direct test (with in vivo sensitized platelets) and an indirect test (with in vitro loaded platelets) were carried out. The percent of rosette forming beads was both in the direct test (41.2%) and in the indirect test (32.6%) significantly higher in the cases of chronic ITP patients than in the controls (2.5% and 3.2%, respectively). These results confirm the diagnostic value of this new, relatively simple and rapid method in routine clinical practice.

Idiopathic thrombocytopenia, initial illness and long term follow up

One hundred and eighty one children with thrombocytopenia for which no cause could be found have been studied. One patient died with severe bleeding possibly from disseminated intravascular coagulation and one developed cerebral haemorrhage, both within two weeks of onset. Ninety one per cent of the 135 with acute disease but only 36% of those with chronic disease remitted spontaneously. Twenty per cent of spontaneous remission occurred more than one year after onset. Six patients have run an intermittent course for 10 to 20 years. Four patients have had symptomless thrombocytopenia for between 10 and 30 years. Of 32 children treated by splenectomy 24 maintained normal platelet values thereafter. One boy died from pneumococcal septicaemia two years after splenectomy but he had not received prophylactic penicillin. One hundred and fifty eight patients were followed up 3 to 37 years (mean 16.4 years) after onset. None who recovered spontaneously or after splenectomy had had further bleeding problems. No patient nor immediate relative had developed other autoimmune disease. We consider that a short course of corticosteroids immediately after diagnosis is justified in all cases even though we cannot produce proof that it influences the course of the disease. We do not accept any place for long term immunosuppressant treatment.