Specific antiplatelet autoantibodies in patients with antiphospholipid antibodies and thrombocytopenia

Primary Immune Thrombocytopenic Purpura (ITP) and ITP Associated with Systemic Lupus Erythematosus: A Review of Clinical Characteristics and Treatment Modalities

Immune thrombocytopenic purpura (ITP) is an immune-mediated disorder characterized by the destruction of platelets and megakaryocytes due to autoantibodies against the platelet surface proteins. ITP without any apparent cause of thrombocytopenia is defined as primary ITP, and ITP in the setting of SLE is secondary ITP, which can be diagnosed after excluding other causes of thrombocytopenia by history, physical examination, and laboratory testing. Patients with ITP associated with SLE have higher median platelet count and less bleeding manifestations compared to the patients with primary ITP. It can be very challenging to diagnose primary ITP in SLE patients as other causes of thrombocytopenia including drug-induced thrombocytopenia, antiphospholipid syndrome, and thrombotic microangiopathic process should be ruled out. Corticosteroids are the main modality of treatment. IVIG can be used in severe cases. Splenectomy was found to be less effective in ITP associated with SLE compared to primary ITP. Control of disease activity with immunosuppressive therapy can be helpful in some cases associated with active disease flares in SLE patients.

Eltrombopag-Induced Thrombocytosis and Thrombosis in Patients With Antiphospholipid Syndrome and Immune Thrombocytopenic Purpura

Antiphospholipid syndrome (APS) may be either as a primary or in association with an underlying systemic autoimmune etiology (36.2%), particularly systemic lupus erythematosus (SLE). Thrombocytopenia is infrequently observed in APS patients, with an occurrence of 22% to 42% with the frequency of thrombocytopenia, higher in APS and SLE combination than in primary APS. There have been some controversial reports regarding the treatment of APS syndrome with thrombocytopenia with TPO agonists. We like to report a case with APS syndrome with severe thrombocytopenia treated with TPO-RA and developed severe thrombocytosis and thrombosis. Our case represented the first case of TPO-RA in treating APS syndrome developed severe thrombocytosis and our case also concurred that use of TPO-RA agents should be strongly discouraged in APS until larger studies clarify the safety of TPO-RA agents in APS.

Cryptic conspirators: a conversation about thrombocytopenia and antiphospholipid syndrome

Purpose of review

Although antiphospholipid syndrome (APS) is best known for conveying increased risk of thrombotic events and pregnancy morbidity, thrombocytopenia is also recognized as a common association. In this review, we will explore the relationship between thrombocytopenia and APS, highlighting our evolving understanding – and persistent knowledge gaps – through clinically oriented questions and answers.

Recent findings

A history of thrombocytopenia likely portends a more severe APS phenotype (including increased risk of thrombosis). Although the pathophysiology underlying thrombocytopenia in APS has yet to be definitively revealed, mechanisms that play a role (at least in subsets of patients) include: immune thrombocytopenic purpura/ITP-like autoantibodies against platelet glycoproteins; antiphospholipid antibody (aPL)-mediated platelet activation and consumption; and potentially life threatening thrombotic microangiopathy. Although thrombocytopenia is often ‘mild’ in APS (and therefore, may not require specific therapy), there are causes of acute-onset thrombocytopenia that mandate emergent work-up and treatment. When APS-related thrombocytopenia does require therapy, the approach must be individualized (requiring an understanding of pathophysiology in the particular APS patient). For patients with ITP-like disease, rituximab is emerging as a popular approach to treatment; in contrast, there are hints that thrombopoietin mimetics may be associated with elevated thrombotic risk.

Summary

Thrombocytopenia is common in APS, and is likely associated with more severe disease. Improved understanding of thrombocytopenia in APS has the potential to improve risk stratification, reveal novel aspects of APS pathophysiology, and lead to treatments that are more individualized and holistic.

The non-haemostatic role of platelets in systemic lupus erythematosus

Dysregulation of lymphocyte function, accumulation of autoantibodies and defective clearance of circulating immune complexes and apoptotic cells are hallmarks of systemic lupus erythematosus (SLE). Moreover, it is now evident that an intricate interplay between the adaptive and innate immune systems contributes to the pathogenesis of SLE, ultimately resulting in chronic inflammation and organ damage. Platelets circulate in the blood and are chiefly recognized for their role in the prevention of bleeding and promotion of haemostasis; however, accumulating evidence points to a role for platelets in both adaptive and innate immunity. Through a broad repertoire of receptors, platelets respond promptly to immune complexes, complement and damage-associated molecular patterns, and represent a major reservoir of immunomodulatory molecules in the circulation. Furthermore, evidence suggests that platelets are activated in patients with SLE, and that they could contribute to the circulatory autoantigenic load through the release of microparticles and mitochondrial antigens. Herein, we highlight how platelets contribute to the immune response and review evidence implicating platelets in the pathogenesis of SLE.

Relevance of antiphospholipid antibody profile in the clinical outcome of ITP: a single-centre study

OBJECTIVES

The relevance of detecting antibodies against anticardiolipin, β2-glycoprotein I (β2gpI) or lupus anticoagulant (LA), collectively called antiphospholipid autoantibodies (APA), in subjects with immune thrombocytopenia (ITP) is still a debated issue. In particular, whether APA profile may affect the clinical course of ITP is unknown.

METHODS

In this study, we report our experience in a cohort of ITP patients with APA with specific interest to the relevance of different antiphospholipid antibody profiles in clinical outcome and response to treatment.

RESULTS

Thirty-seven out of 159 patients (23.2%) fulfilling ITP criteria had a platelet count ≤50 × 10⁹/L and tested positive at APA at ITP onset. Twenty-three (62.1%) patients received at least one line of treatment for ITP. Fourteen subjects (37.8%) showing triple positivity for APA showed a significantly lower median platelet count compared to other APA patients (p = .006). Among these ITP subjects with triple positivity, 85.7% needed a treatment because of low platelet count compared to 47.8% ITP patients with non-triple-positive APA (p = .0094). ITP/APA subjects who received immunosuppressors had a higher rate of thrombosis (p = .024) as well as thrombosis developed in subjects who were on steroid therapy at a significantly higher dosage than subjects who did not develop thrombotic episodes (p < .001). When considering treatment, CR and SR rate were significantly higher in ITP/triple-positive patients compared to non-triple-positive subjects (p = .021 and p = .005).

CONCLUSIONS

The profile of APA may affect the outcome of patients with ITP.

Lupus thrombocytopenia: pathogenesis and therapeutic implications

Systemic Lupus Erythematosus (SLE) is frequently complicated by cytopenias. Thrombocytopenia is usually non severe and its frequency ranges from 20% to 40%. It is mostly an autoimmune process caused by autoantibodies against platelet surface glycoproteins and it is associated with worse prognosis in SLE. It can also be a result of SLE treatment with azathioprine, methotrexate and rarely hydroxychloroquine or thrombotic microangiopathy or macrophage activation syndrome. If thrombocytopenia is mild (>50×10⁹/L) and there is no other evidence of disease there is no need of therapy. Severe thrombocytopenia is less frequent and needs therapeutic management. Corticosteroids are the cornerstone of therapy. Continuous high dose oral prednisolone or pulse high dose methylprednisolone (MP) with or without intravenous immune globulin are used in the acute phase. Second line agents (hydroxychloroquine, danazol, azathioprine, cyclosporine, mycophenolate mofetil, cyclophosphamide, rituximab) are usually needed. Splenectomy is indicated for recurrent or resistant cases. There are no evidence-based guidelines to facilitate selection of one drug over another but certainly the co-existence of other systemic SLE manifestations must be taken into account. Newer therapies are emerging although there is no consensus on the treatment of refractory lupus thrombocytopenia due to the absence of controlled randomized trials.

Antiphospholipid antibody associated thrombocytopenia and the paradoxical risk of thrombosis

The pathogenesis of thrombocytopenia in patients with antiphospholipid syndrome (APS) is heterogeneous. Patients with antiphospholipid antibodies (aPL) and thrombocytopenia in the absence of clinical manifestations of APS will be diagnosed and treated as idiopathic thrombocytopenic purpura. However, the presence of aPL places those individuals at particular risk for developing both bleeding and thrombotic complications. Therefore, we propose the inclusion of such patients in the subgroup ‘aPL-associated thrombocytopenia’. More attention should be devoted to this subgroup of patients to elucidate the role of aPL in the development of thrombocytopenia and to facilitate the adequate monitoring of its potential thrombotic risk.

The significance and management of thrombocytopenia in antiphospholipid syndrome

The association between antiphospholipid antibodies (aPL) and clinical problems goes beyond what is stated in the antiphospholipid syndrome (APS) classification criteria, namely thrombosis and pregnancy morbidity, and thrombocytopenia is the most common non-criteria hematologic manifestation of aPL with a frequency ranging from 20 to 50 %. Thrombocytopenia is rarely severe, and hemorrhage is far less common than thrombosis. However, when anticoagulation is considered, it may constitute a clinical problem with increased bleeding risk. Furthermore, thrombocytopenia represents a risk factor for thrombosis in aPL-positive patients. Therefore, it is important to understand the pathogenesis and the clinical associations of thrombocytopenia to build the right medical approach in aPL-positive patients. In this paper, we review the literature on aPL/APS-associated thrombocytopenia and briefly discuss the other conditions that can result in thrombocytopenia as they have commonalities with APS and their recognition is important to establish the most appropriate treatment strategy.

Haematological manifestations of lupus

Our purpose was to compile information on the haematological manifestations of systemic lupus erythematosus (SLE), namely leucopenia, lymphopenia, thrombocytopenia, autoimmune haemolytic anaemia (AIHA), thrombotic thrombocytopenic purpura (TTP) and myelofibrosis. During our search of the English-language MEDLINE sources, we did not place a date-of-publication constraint. Hence, we have reviewed previous as well as most recent studies with the subject heading SLE in combination with each manifestation. Neutropenia can lead to morbidity and mortality from increased susceptibility to infection. Severe neutropenia can be successfully treated with granulocyte colony-stimulating factor. While related to disease activity, there is no specific therapy for lymphopenia. Severe lymphopenia may require the use of prophylactic therapy to prevent select opportunistic infections. Isolated idiopathic thrombocytopenic purpura maybe the first manifestation of SLE by months or even years. Some manifestations of lupus occur more frequently in association with low platelet count in these patients, for example, neuropsychiatric manifestation, haemolytic anaemia, the antiphospholipid syndrome and renal disease. Thrombocytopenia can be regarded as an important prognostic indicator of survival in patients with SLE. Medical, surgical and biological treatment modalities are reviewed for this manifestation. First-line therapy remains glucocorticoids. Through our review, we conclude glucocorticoids do produce a response in majority of patients initially, but sustained response to therapy is unlikely. Glucocorticoids are used as first-line therapy in patients with SLE with AIHA, but there is no conclusive evidence to guide second-line therapy. Rituximab is promising in refractory and non-responding AIHA. TTP is not recognised as a criteria for classification of SLE, but there is a considerable overlap between the presenting features of TTP and SLE, and a few patients with SLE have concurrent TTP. Myelofibrosis is an uncommon yet well-documented manifestation of SLE. We have compiled the cases that were reported in MEDLINE sources.

Task Force on Catastrophic Antiphospholipid Syndrome (APS) and Non-criteria APS Manifestations (II): thrombocytopenia and skin manifestations

The objectives of the ‘Task Force on Catastrophic Antiphospholipid Syndrome (APS) and Non-criteria APS Manifestations’ were to assess the clinical utility of the international consensus statement on classification criteria and treatment guidelines for the catastrophic APS, to identify and grade the studies that analyze the relationship between the antiphospholipid antibodies and the non-criteria APS manifestations, and to present the current evidence regarding the accuracy of these non-criteria APS manifestations for the detection of patients with APS. This article summarizes the studies analyzed on thrombocytopenia and skin manifestations, and presents the recommendations elaborated by the Task Force after this analysis.

Antiphospholipid-associated thrombocytopenia or autoimmune hemolytic anemia in patients with or without definite primary antiphospholipid syndrome according to the Sapporo revised classification criteria: a 6-year follow-up study

The updated Sapporo classification criteria for antiphospholipid syndrome (APS) only include thrombosis or pregnancy morbidity as clinical criteria. To test this notion, we studied 55 patients (80% women) with hematologic manifestations. All fulfilled the laboratory criteria for primary APS. Thirty-five patients (64%) had thrombocytopenia, 14 (25%) had autoimmune hemolytic anemia, and 6 (11%) had both. Twenty-five patients (22 women, 88%) also fulfilled one clinical criterion for APS after a median follow-up of 13.2 years (range, 1.45-37 years), whereas the remaining 30 patients (22 women, 73%) have not had any thrombotic event nor pregnancy morbidity after a median follow-up of 5.4 years (range, 0.12-24 years). No patient developed systemic lupus erythematosus during follow-up. The hematologic manifestation was asynchronous with the APS onset in 84% of patients. The response to treatment was similar regardless of the APS status. Patients with definite APS were more frequently positive for the lupus anticoagulant (63%) than lupus anticoagulant-positive patients without APS (30%; odds ratio, 3.5; 95% confidence interval, 1.07-11.4; P < .02). Anticardiolipin or anti–β2-glycoprotein-I antibodies were highly prevalent among the study groups. Our study suggests that, depending upon their antiphospholipid profile, patients with hemocytopenias appear to comprise a peculiar subset of patients with APS; some develop thrombotic and/or obstetric APS whereas others continue with hematologic APS.

Therapeutic approaches to secondary immune thrombocytopenic purpura

Secondary thrombocytopenia is similar to primary or idiopathic thrombocytopenia (ITP) in that it is characterized by reduced platelet production or increased platelet destruction resulting in platelet levels<60,000/microL. Thrombocytopenia can occur from secondary causes associated with chronic disorders or with disturbed immune function due to chronic infections, lymphoproliferative and myeloproliferative disorders, pregnancy, or autoimmune disorders. Diagnosis of secondary ITP in some cases is complex, and the thrombocytopenia can often be resolved by treating the underlying disorder to the extent this is possible. In most cases, treatment is focused on reducing platelet destruction, but, in some cases, treatment may also be directed at stimulating platelet production. The most problematic cases of thrombocytopenia may be seen in pregnant women. This review will address various agents and their utility in treating ITP from secondary causes; in addition, thrombocytopenia in pregnancy, ITP in immunodeficiency conditions, and drug-induced thrombocytopenia will be discussed. Unlike primary ITP, treatment often must be tailored to the specific circumstance underlying the secondary ITP, even if the condition itself is incurable.

Pathobiology of secondary immune thrombocytopenia

Primary immune thrombocytopenic purpura (ITP) remains a diagnosis of exclusion both from nonimmune causes of thrombocytopenia and immune thrombocytopenia that develops in the context of other disorders (secondary immune thrombocytopenia). The pathobiology, natural history, and response to therapy of the diverse causes of secondary ITP differ from each other and from primary ITP, so accurate diagnosis is essential. Immune thrombocytopenia can be secondary to medications or to a concurrent disease, such as an autoimmune condition (eg, systemic lupus erythematosus [SLE], antiphospholipid antibody syndrome [APS], immune thyroid disease, or Evans syndrome), a lymphoproliferative disease (eg, chronic lymphocytic leukemia or large granular T-lymphocyte lymphocytic leukemia), or chronic infection, eg, with Helicobacter pylori, human immunodeficiency virus (HIV), or hepatitis C virus (HCV). Response to infection may generate antibodies that cross-react with platelet antigens (HIV, H pylori) or immune complexes that bind to platelet Fcγ receptors (HCV), and platelet production may be impaired by infection of megakaryocyte (MK) bone marrow–dependent progenitor cells (HCV and HIV), decreased production of thrombopoietin (TPO), and splenic sequestration of platelets secondary to portal hypertension (HCV). Sudden and severe onset of thrombocytopenia has been observed in children after vaccination for measles, mumps, and rubella or natural viral infections, including Epstein-Barr virus, cytomegalovirus, and varicella zoster virus. This thrombocytopenia may be caused by cross-reacting antibodies and closely mimics acute ITP of childhood. Proper diagnosis and treatment of the underlying disorder, where necessary, play an important role in patient management.

The role of complement regulatory proteins (CD55 and CD59) in the pathogenesis of autoimmune hemocytopenias

Mammalian cells are provided with surface-bound complement regulatory proteins that protect them from uncontrolled complement-mediated lysis. Two of these regulators in humans, CD55 and CD59, are glycosylphosphatidylinositol-anchored, type I cell surface proteins, which inhibit formation of the C3 convertases and prevent the terminal polymerization of the membrane attack complex, respectively. Paroxysmal nocturnal hemoglobinuria is a genetic disorder due to the impaired conformation of the glycosylphosphatidylinositol-anchor, that results in the deficient expression of CD55 and CD50 which leads to excessive destruction of red cells and leukocytes. We have studied the expression of these two molecules in patients with autoimmune hemolytic anemia, autoimmune thrombocytopenia, and patients with systemic lupus erythematosus showing lymphopenia, and found that all three types of cytopenias are associated to deficient expression of CD55 and CD59 on the involved hematopoietic lineage. These are the first descriptions of acquired deficiencies of complement regulatory molecules in human disease, and it seems, from our results, that such deficiencies might play a pathogenic role in the mechanism of cell destruction. Although autoantibodies appeal as the best candidates to cause underexpression of CD55 and CD59, the search for an association to the presence and titers of most frequent self-reactive antibodies has proved non-existent.

Helicobacter pylori eradication: novel therapy for immune thrombocytopenic purpura? A review of the literature

Eradication of Helicobacter pylori (H. pylori ) from the gastric mucosa has been associated with improvement of several systemic diseases, including immune thrombocytopenic purpura (ITP). Over the last 5 years, several studies have reported improved platelet counts in H. pylori-positive ITP patients following standard triple H. pylori eradication therapy. Review of published studies in which eradication of H. pylori has been performed in the ITP population indicates an overall response rate of 52% in 193 subjects in whom H. pylori was eradicated. Cohorts from Japan and Italy report higher response rates. There is no established mechanism to explain how this organism, which does not invade the gastric mucosa, could be implicated in the pathogenesis of this immune-based platelet disorder. Several theories including molecular mimicry, platelet aggregation, and immunomodulatory effects of macrolides have been proposed to explain the platelet response to anti-H. pylori therapy. Large randomized-controlled studies enrolling patients from various ethnic backgrounds will be necessary to determine the response rate and mechanism of response and to gain a better understanding of the pathogenesis of ITP.

Antiphospholipid antibodies in immune thrombocytopenic purpura tend to emerge in exacerbation and decline in remission

Although the presence of antiphospholipid antibodies (APLA) in immune thrombocytopenic purpura (ITP) has been reported, their clinical significance is not clear. The present study investigated APLA profiles in relation to the clinical stages of ITP. We studied APLA in 40 patients in three stages of ITP: exacerbation/relapse (n=7), stable (n=14) and remission (n=19). Both IgG and IgM APLA to six target antigens were measured by enzyme-linked immunosorbent assay: beta2-glycoprotein 1 (beta2GP1), cardiolipin, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and factor VII/VIIa. The central finding was that APLA were common in ITP but differed significantly in disease stages, being highest in exacerbation (86% positive), intermediate in stable disease (57%) and lowest in remission (42%). In exacerbations, APLA were predominantly of IgG class, while in stable disease, IgM predominated. During remission, APLA often became undetectable. Both the frequency and titres of APLA were significantly higher during exacerbation than remission. An inverse correlation was found between platelet count and nearly all APLA (except beta2GP1). Sequential study of six patients revealed that APLA tended to emerge and rise with exacerbation, concurrently with new episodes of bleeding and became undetectable during remission. These findings raise the possibility that APLA may play a role in the exacerbation and remission of ITP or they may be a consequence of platelet destruction.

Antiphospholipid antibodies and antiphospholipid syndrome in patients presenting with immune thrombocytopenic purpura: a prospective cohort study

The pathogenetic role and the clinical importance of the presence of antiphospholipid antibodies (APAs) in patients with immune thrombocytopenic purpura (ITP) are not clear. In this study, the prevalence and clinical significance of APAs were investigated in patients with ITP. Eighty-two newly diagnosed ITP patients were prospectively studied. They were evaluated for the presence of lupus anticoagulant (LA) and immunoglobulin G/M anticardiolipin antibodies (ACAs). Thirty-one patients (37.8%) were APA positive at diagnosis. No statistically significant differences were found between the APA-positive and APA-negative groups regarding gender, initial platelet counts, or response to methylprednisolone therapy. After 5 years of follow-up, cumulative thrombosis-free survival of APA-positive (n = 31) and APA-negative (n = 51) ITP patients was 39% and 97.7%, respectively. A significant difference was found between these groups by log-rank test (P =.0004). In addition, LA was an important risk marker for the development of thrombosis in ITP patients. After a median follow-up of 38 months, 14 ITP patients (45%) who had APA positivity developed clinical features (thrombosis or fetal losses) of antiphospholipid syndrome (APS). There were no differences between the APA-positive patients with and without APS regarding the initial platelet counts, response to the therapy, or ACA positivity. The positivity rate for LA was significantly higher in those patients with ITP who developed APS (chi(2): P =.0036; relative risk 7.15; 95% confidence interval, 1.7-47). In conclusion, this study indicates that a significant proportion of patients initially presenting with ITP and APA positivity developed APS. In patients with ITP, the persistent presence of APAs is an important risk factor for the development of APS.

Clinical study and follow-up of 100 patients with the antiphospholipid syndrome

OBJECTIVES

To study the clinical characteristics at diagnosis and during follow-up of patients with the antiphospholipid syndrome (APS) and to analyze the influence of treatment on their outcome.

PATIENTS

One hundred patients with APS were included (86% female and 14% male; mean age, 36 years). Sixty-two percent had primary APS and 38% had APS associated with systemic lupus erythematosus (SLE). The median length of follow-up was 49 months.

RESULTS

Fifty-three percent of the patients had thromboses, 52% had thrombocytopenia, and 60% of the women had pregnancy losses. Patients with APS associated with SLE had a higher prevalence of hemolytic anemia (P = .02), thrombocytopenia (platelet count lower than 100 x 10(9)/L) (P = .004), antinuclear antibodies (P = .0002), and low complement levels. Fifty-three percent of the patients with thrombosis had recurrent episodes (86% in the same site as the previous thrombotic event). Recurrences were observed in 19% of the episodes treated with long-term oral anticoagulation, in 42% treated prophylactically with aspirin, and in 91% in which anticoagulant/antiaggregant treatment was discontinued (P = .0007). Multivariate analysis showed that prophylactic treatment and older age had an independent predictive value for rethrombosis. Prophylactic treatment during pregnancy (usually with aspirin) increased the live birth rate from 38% to 72% (P = .0002).

CONCLUSIONS

Patients with APS have a high risk of recurrent thromboses. Long-term oral anticoagulation seems to be the best prophylactic treatment to prevent recurrences. Prophylactic treatment with aspirin during pregnancy reduced the rate of miscarriages remarkably.

Splenectomy for refractory thrombocytopenia in the antiphospholipid syndrome

OBJECTIVE

Thrombocytopenia, usually mild, is one of the clinical criteria of the antiphospholipid syndrome (APS). Rarely, this disorder requires treatment and, due to the shared characteristics with idiopathic thrombocytopenic purpura (ITP), similar rules are followed. We report our experience in patients who required splenectomy after being refractory to steroids and immunosuppressive therapy.

METHODS

Fifty-five APS patients with a platelet count of < 100 x 10(9)/l at least twice were analysed retrospectively. Therapeutic response or remission was considered when the platelet count was > 100 x 10(9)/l after 1 month and with no relapse on stopping or tapering the steroid dose. No response or refractory disease was defined as an absence of increase in platelet count, a total count that never exceeded 50 x 10(9)/l during treatment or when the dose requirements were such that the patient developed serious side-effects.

RESULTS

Fifty patients were classified as having secondary APS associated with systemic lupus erythematosus (SLE) and five were identified as primary APS (PAPS). Splenectomy was performed in 11 cases (20%), two PAPS and nine SLE-APS, with an average time of 28 +/- 9 months after the development of thrombocytopenia. Eight patients were initially characterized as ITP (six SLE-APS, two PAPS) with an average time of 4.4 +/- 1.1 yr until the APS diagnosis. All but two were responsive to splenectomy.

CONCLUSION

Splenectomy was required in 11 (20%) of the patients with APS-associated thrombocytopenia. There was a high rate of good and long-term response.

[Antiphospholipid antibody syndrome]

BACKGROUND

Antiphospholipid antibodies comprise a family of auto-antibodies mainly characterized by the presence of the lupus anticoagulant (LA) and anticardiolipin antibodies (ACA).

CLINICAL APPEARANCE

The antiphospholipid antibody syndrome is defined by the appearance of frequent thromboses, repeated fetal losses and thrombocytopenia. Other clinical manifestations associated with APA include migraine, chorea, hemolytic anemia, heart valve disease, Budd-Chiari syndrome, perpetual pancreatitic episodes, intestinal infarctions, malignant hypertension, livedo reticularis, pre-eclampsia, fetal growth retardation or catastrophic antiphospholipid syndrome. LA and ACA occur in a variety of clinical conditions (secondary antiphospholipid antibody syndrome, SAPS), including other autoimmune disorders, infectious diseases, neoplastic disorders, in association with the use of certain drugs or in otherwise healthy individuals (primary antiphospholipid antibody syndrome, PAPS).

TREATMENT

Patients with thrombosis associated with APA should receive long-term anticoagulation therapy, whereas treatment of asymptomatic patients seems to be not indicated, because only approximately 10% of patients with APA may develop thrombotic complications. In patients with PAPS there is no evidence that the prophylactic administration of immunosuppressive drugs will prevent thromboembolic events.

Simultaneous onset of alopecia areata and idiopathic thrombocytopenic purpura: A potential association?

Alopecia areata (AA) has been associated with a variety of autoimmune diseases. Immune thrombocytopenic purpura (ITP) is an autoimmune disease marked by isolated thrombocytopenia. We present a young girl with the simultaneous onset of AA and ITP. To the best of our knowledge, this association has not previously been reported. We hypothesize that ITP may be one of many autoimmune diseases associated with AA via antibodies that cross-react between platelet membrane glycoproteins and follicular glycoproteins.

Evans's Syndrome with Positive Lupus Anticoagulant and Antiphospholipid-Protein Antibodies

We report a case of a 34-year-old Caucasian man with Evans's syndrome, first manifested in childhood as autoimmune thrombocytopenia. Besides anti-erythrocyte antibodies and platelet-associated immunoglobulins, this patient's serum showed also the presence of antiphospholipid-protein antibodies detected by coagulometric (lupus anticoagulant) as well as immunoenzymatic methods (anticardiolipin, antiprothrombin, and anti-β2-glycoprotein I antibodies). Over 25 years of clinical observation the patient never experienced any thromboembolic events. We suggest that in the pathogenesis of Evans's syndrome and related disorders a major role is played by an autoimmune reaction with a predilection to various cell phospholipid-containing membrane structures, possibly damaged by a yet unknown primary insult. The significance of these various antiphospholipid-protein antibodies as predictors of thromboembolic complications in such patients remains, however, to be established. Key Words: Evans's syndrome-Lupus anticoagulant-Antiphospholipid-protein antibodies.

Chronic isolated macrothrombocytopenia with autosomal dominant transmission: a morphological and qualitative platelet disorder

We studied 47 subjects belonging to 13 unrelated families with a history of mild haemorrhagic diathesis and chronic thrombocytopenia. 36 patients presented some degree of thrombocytopenia: 7/36 (19%) had slight thrombocytopenia (100-150 x 10(9)/L); 26/36 (72%) had mild thrombocytopenia (50-100 x 10(9)/L) and 3/36 (8%) had severe thrombocytopenia (< 50 x 10(9)/L). No correlation was observed between platelet count and the degree of haemorrhagic diathesis, which was mild in the majority of patients. Transmission was autosomal dominant. Platelet anisocytosis, increased percentage of large platelets and absence of leukocyte inclusions were observed in 26/30 (87%) of the examined blood smears. The ultrastructural appearance of platelets was normal. Megakaryocytes appeared normal in number in 10/10 patients, but showed asynchronous nuclear-cytoplasm maturation and mainly nonlobulated nuclei. Platelet aggregation was studied in 26 patients and either increased or decreased curves were variably observed in response to different aggregating agents. Platelet-associated IgG (PAIgG) was increased in 18/31 (58%) patients, while serum autoantibodies against platelet glycoproteins Ib/IX or IIb/IIIa were demonstrable in only 1 case. An increased expression of platelet surface glycoproteins Ib and IIb/IIIa, as studied by murine monoclonal antibodies binding in 17 cases, was observed. Platelet survival performed by 111Inoxine-labelled autologous platelets was normal in the 3 studied patients. Congenital macrothrombocytopenia confirms to be a distinct clinical disorder for which the name of "chronic isolated hereditary macrothrombocytopenia" is proposed.

Antiplatelet glycoprotein autoantibodies in patients with autoimmune diseases with and without thrombocytopenia

The presence and specificity of antiplatelet autoantibodies in 32 patients with primary and 18 patients with secondary autoimmune thrombocytopenic purpura (AITP), as well as 11 non-thrombocytopenic patients with systemic autoimmune diseases, were studied. By means of the direct and indirect monoclonal antibody immobilization of platelet antigen (MAIPA) assay, antiplatelet autoantibodies were detected using monoclonal antibodies specific for platelet glycoproteins (GPs) Ib, IIb/IIIa, Ia/IIa, and IV. Serum antiplatelet autoantibodies were found in 18 of 32 primary AITP patients (56%), 6 of 18 secondary AITP patients (33%), and 5 of 11 nonthrombocytopenic patients (45%). Platelet-associated autoantibodies were detected in five of eight patients with primary (62%) and in four of eight patients with secondary AITP (50%) and in two of four patients without thrombocytopenia (50%). Multiple antibody reactivity, mainly against GPs IIb/IIIa and Ib and, in a few patients, against Ia/IIa, was found. Using MAIPA, platelet xylene eluates from 20 patients were also studied. Antiplatelet elutable autoantibodies were related to thrombocytopenia; autoantibodies against membrane GPs Ib and IIb/IIIa were demonstrable in 84 and 63% of eluates from patients with primary and secondary AITP, respectively, but not in eluates from nonthrombocytopenic patients. The presence of antiplatelet antibodies thus appears to be a common feature of many autoimmune diseases apart from the thrombocytopenia, but the (primary or secondary) etiology of the immune thrombocytopenia cannot be differentiated on the grounds of their specificity.

Platelets and antiphospholipid antibodies

The involvement of platelets in the antiphospholipid syndrome is complex and the full pathogenic significance is not fully understood. The binding of aPL antibodies to the platelet membrane may result in the thrombopenia and further haemostatic activation.

1996 diagnostic and classification criteria for the antiphospholipid/cofactors syndrome: a "mission impossible'?

Due to recent acquisitions, diagnostic criteria for the antiphospholipid/cofactors syndrome need to be improved. In the absence of a "common biological denominator", the best approach should be based on a scoring system mixing clinical and immunological items. APS might be composed of different biological subsets characterized by antibodies directed to various cofactors. Among clinical subsets, the categorization between "primary" and SLE-related APS may be difficult to achieve. Contrasting with the innumerable conditions associated with the presence of aPL, the diversity of "true" secondary APS should probably be restrained. Attempts at establishing correlations between clinical and biological APS subsets will require further studies.

Prevalence of antibodies to cardiolipin in chronic ITP and reactivity with platelet membranes

Anti-cardiolipin antibodies (ACLA) have been suggested to play a role in the pathogenesis of thrombocytopenia. When sera from 40 patients with chronic idiopathic thrombocytopenic purpura (ITP) were analyzed for ACLA, these autoantibodies were present in 12 (30%). In 4 sera the antibody activity was restricted to the IgG or IgM isotype, respectively, while 4 of the samples contained both IgG and IgM antibodies. To elucidate the interaction between platelets and ACLA, we studied the reactivity of sera from non-ITP patients with ACLA, with fragmented platelet membranes. None of them had a concurrent platelet deficiency, but sera from 8 (67%) of them showed increased IgG-binding to platelet membranes. Absorbtion with cardiolipin reduced membrane binding in 6 (50%). C3 levels were normal, while low C4 values occurred in both groups with significantly lower levels in ACLA-positive patients (p<0.05). Circulating immune complexes (CIC) were common in both groups.

CONCLUSION

The prevalence of ACLA is increased in ITP and sera from non-ITP patients with ACLA react with fragmented platelet membranes. This reactivity is often decreased by absorption with cardiolipin, suggesting that ACLA bind to phospholipid epitopes on platelet membranes.

The lupus anticoagulant/antiphospholipid syndrome

Lupus anticoagulants and anticardiolipin antibodies have been strongly associated with the risk of thrombosis, recurrent fetal loss, thrombocytopenia, and a number of other clinical manifestations that together have been referred to as the antiphospholipid syndrome. Despite growing evidence of the significance of this relationship, the pathogenetic mechanisms involved are largely unknown. Recent data suggest strongly that lupus anticoagulants (LACs) and anticardiolipin antibodies (ACAs) are antibodies to protein-phospholipid complexes rather than to phospholipids, as had originally been thought, and that other protein-phospholipid complexes, not recognized by standard assays for LACs or ACAs, may also exist in patients with the antiphospholipid syndrome. Although very recent experimental data may lead to new therapeutic approaches in this syndrome, at present we can only deal with the thrombotic risk by the use of long-term anticoagulation. This chapter reviews current methods of diagnosis, concepts of pathogenesis, and the basis for an approach to anticoagulation in patients at risk for thrombosis or other manifestations of the antiphospholipid syndrome.