Inter-relationships between platelet count,platelet IgG,serum IgG,immune complexes and severity of liver disease

Summary Thrombocytopenia is a common finding in subjects with chronic liver diseases. A variety of mechanisms may underlie this. Immunological disturbances are commonly a feature in chronic liver disease, including hyperglobulinaemia and the presence of autoantibodies and circulating immune complexes and immune mechanisms could therefore contribute to thrombocytopenia. We have investigated the relationships between blood platelet count, serum IgG and IgG immune complexes and IgG associated with platelets in 92 subjects with chronic liver disease (27 with chronic active hepatitis, 38 with primary biliary cirrhosis and 27 with alcoholic liver disease). Severity of liver impairment was a major determinant of degree of thrombocytopenia. Also, an inverse relationship was demonstrated between platelet count and platelet-associated IgG. In subjects with chronic active hepatitis the relationships between platelet count, serum IgG immune complexes and platelet-associated IgG were consistent with a role for immune mechanisms in general and immune complexes in particular as mediators of the thrombocytopenia.     

Thrombokinetics in patients with rheumatoid arthritis treated with D-penicillamine.

The mechanism of D-penicillamine induced thrombocytopenia in rheumatoid arthritis was investigated by measuring platelet life-span and platelet production rate in 2 groups of rheumatoid arthritis patients treated with 250-750 mg/day D-penicillamine, 14 with a normal platelet count and 9 with thrombocytopenia (platelet count 50-130 X 10(9)/1). Age matched control patients not treated with D-penicillamine included 14 with rheumatoid arthritis and 9 with osteoarthritis. The platelet life-span was normal, but platelet production rate was significantly reduced in the thrombocytopenic patients, suggesting that D-penicillamine causes thrombocytopenia through bone marrow suppression.     

Life-threatening severe immune thrombocytopenia during alpha-interferon therapy for chronic hepatitis C

Although mild thrombocytopenia is a common adverse effect of interferon therapy, severe life-threatening thrombocytopenia is extremely rare. Here, we report a case of chronic hepatitis C patient that developed severe thrombocytopenia during alpha-interferon therapy, possibly due to an autoimmune mechanism. A 24-year-old female presented chronic hepatitis C in May, 1998. Based on the clinicopathological findings including a liver biopsy, administration of alpha-interferon was begun. In the fourth week of therapy, she experienced mild dyspnea and general fatigue. Complete blood count demonstrated thrombocytopenia (48,000/microL). Despite the immediate withdrawal of interferon, her platelet count further decreased to 1,100/microL. Bone marrow aspirate and elevated platelet-associated IgG antibodies were suggestive of immune thrombocytopenia. She was treated with intravenous and oral administration of steroids. Her platelet count returned to normal level 5 days later. Response to steroid treatment was consistent with the diagnosis of alpha-interferon-induced immune thrombocytopenia in this patient.     

Immune thrombocytopenia: effects of maternal gamma globulin infusion on maternal and fetal serum, platelet, and monocyte IgG

A 24-year-old woman with lupus-like serologic abnormalities had immune thrombocytopenia that resolved after splenectomy, but increased quantities of platelet surface IgG persisted. Three years later, during the 36th week of her first pregnancy, gamma globulin (400 mg/kg daily for 5 days) was administered intravenously to decrease the risk and/or severity of immune thrombocytopenia in her infant. The infusion produced marked but transient elevations of maternal concentrations of serum IgG and quantities of monocyte surface IgG, but no significant changes in Fc receptor-mediated rosetting of peripheral blood monocytes with antibody-sensitized platelets occurred. Modest increases in quantities of platelets and plasma platelet-specific IgG were demonstrated. The infant, delivered by cesarean section 2 days after the end of the infusion, had a normal platelet count; cord blood had a normal concentration of serum IgG, but an elevated quantity of platelet surface IgG (by comparison with values for normal adults). Infant values of plasma platelet-specific IgG, monocyte surface IgG, and monocyte/platelet rosettes also were within the range of normal for adults. Anticytomegalovirus antibody was present in large amounts in the gamma globulin infused, first appeared in maternal serum after therapy, and was detected in cord serum. The significance of these observations to the management of immune neonatal thrombocytopenia is discussed.     

Piperacillin and vancomycin induced severe thrombocytopenia in a hospitalized patient

In hospitalized patients with complex medical problems on numerous drugs, thrombocytopenia may have a multiple confounding etiology. Keeping this in mind, it is of utmost importance to monitor the platelet count regularly during hospitalization and on subsequent follow-up visits, even after the most probable etiology has been identified/most likely causative drug has been withdrawn. Isolated thrombocytopenia with no evidence of microangiopathic hemolysis on the peripheral blood smear in an acutely ill hospitalized patient implicated sepsis, disseminated intravascular coagulation and drugs as the most probable causes. Our patient represents an uncommon case of antibiotic-induced severe immune thrombocytopenia, as he developed both vancomycin-dependent and piperacillin-dependent antibodies, while being treated for cellulitis (vancomycin-specific antibodies of the IgG isotype, and both IgG and IgM antibodies specific for piperacillin were identified in laboratory testing). Vancomycin was stopped before the reports were available. Following this, the patient's platelet count showed a transient upward trend, but then the thrombocytopenia worsened drastically reaching a nadir of 10,000/μL. The platelet count returned to normal only after piperacillin/tazobactam was stopped after a week, thus establishing it as the cause of the more severe thrombocytopenia, which occurred later on; this was subsequently confirmed by the laboratory results. Vancomycin is an established cause of drug-induced immune thrombocytopenias, especially in acutely ill, hospitalized or elderly patients, whereas incidents of piperacillin/tazobactam-induced immune thrombocytopenia are uncommon. In case clinical suspicion is high, workup should include immunoprecipitation and flow cytometry studies to confirm antiplatelet antibodies.     

The treatment of neonatal isoimmune thrombocytopenia with intravenous immunoglobin (IgG i.v.)

Summary We present a report of the use of IgG i.v. to treat clinically manifest neonatal immune thrombocytopenia. The IgG i.v. was administered at a daily dosage of 0.4 g/kg body weight for 5 days. Treatment was started when the child was 3 days old and had a platelet count of 2×10⁹/l. Four days later the platelet count had risen to 200×10⁹/l. The diagnosis of immune thrombocytopenia was confirmed by platelet typing of the mother's and child's platelets and identification of anti-platelet antibodies in maternal serum.     

IgG-associated immune thrombocytopenia in Waldenstr?m macroglobulinemia

Waldenstr?m macroglobulinemia (WM) is characterized by serum IgM monoclonal gammopathy, and only occasionally complicated by immune thrombocytopenia. Rarely, coexistence of non-IgM gammopathy in WM has been reported. Herein, we describe an 81-year-old case of WM with rapidly progressive immune thrombocytopenia accompanied by concurrent IgG gammopathy and elevation of platelet-associated IgG (PA-IgG). Immunostaining of the bone marrow specimen displayed not only IgM positive but also IgG positive plasmacytoid cells. Although dexamethasone therapy had no effect on thrombocytopenia, a modified RCD regimen (rituximab 375 mg/m² i.v. day 1, cyclophosphamide 375 mg/m² i.v. day 2 and dexamethasone 12 mg/body orally days 1–7) successfully normalized PA-IgG as well as IgG and IgM paraproteinemia and significantly increased platelet count. The current case suggests that the IgG gammopathy associated with WM is likely to be an etiology of immune thrombocytopenia and that tumor reduction, rather than immunosuppression, leads to an improvement of concurrent thrombocytopenia.     

Piperacillin and vancomycin induced severe thrombocytopenia in a hospitalized patient

In hospitalized patients with complex medical problems on numerous drugs, thrombocytopenia may have a multiple confounding etiology. Keeping this in mind, it is of utmost importance to monitor the platelet count regularly during hospitalization and on subsequent follow-up visits, even after the most probable etiology has been identified/most likely causative drug has been withdrawn. Isolated thrombocytopenia with no evidence of microangiopathic hemolysis on the peripheral blood smear in an acutely ill hospitalized patient implicated sepsis, disseminated intravascular coagulation and drugs as the most probable causes. Our patient represents an uncommon case of antibiotic-induced severe immune thrombocytopenia, as he developed both vancomycin-dependent and piperacillin-dependent antibodies, while being treated for cellulitis (vancomycin-specific antibodies of the IgG isotype, and both IgG and IgM antibodies specific for piperacillin were identified in laboratory testing). Vancomycin was stopped before the reports were available. Following this, the patient's platelet count showed a transient upward trend, but then the thrombocytopenia worsened drastically reaching a nadir of 10,000/µL. The platelet count returned to normal only after piperacillin/tazobactam was stopped after a week, thus establishing it as the cause of the more severe thrombocytopenia, which occurred later on; this was subsequently confirmed by the laboratory results. Vancomycin is an established cause of drug-induced immune thrombocytopenias, especially in acutely ill, hospitalized or elderly patients, whereas incidents of piperacillin/tazobactam-induced immune thrombocytopenia are uncommon. In case clinical suspicion is high, workup should include immunoprecipitation and flow cytometry studies to confirm antiplatelet antibodies.     

Inflammatory abdominal aortic aneurysm followed by disseminated intravascular coagulation and immune thrombocytopenia

A 71-year-old man was diagnosed as having an abdominal aortic aneurysm when he was treated for idiopathic interstitial pneumonia (IIP). Three years later, he developed severe thrombocytopenia and had disseminated intravascular coagulation (DIC) that was associated with the inflammatory abdominal aortic aneurysm (IAAA). The coagulation abnormalities were corrected by low-molecular weight heparin, however the platelet count remained low. Bone marrow showed normocellularity with an increase of immature and mature forms of megakaryocytes. Platelet-associated IgG level was high. These findings suggested that the patient had severe thrombocytopenia caused by unusual complications of immune thrombocytopenic purpura and IAAA-associated DIC.     

Critical role of CD4(+)CD25(+) regulatory T cells in preventing murine autoantibody-mediated thrombocytopenia

Autoimmune response suppression by regulatory T cells (Tregs) helps to maintain peripheral immune tolerance, and defects in this mechanism are thought to play a role in the pathogenesis of various autoimmune diseases. In patients with immune thrombocytopenia, naturally occurring CD4(+)CD25(+) Tregs are both functionally impaired and reduced in number. This?study was undertaken to investigate Tregs' role in preventing immune thrombocytopenia in mice. Treg-deficient mice were prepared by inoculation of Treg-depleted CD4(+)CD25(-) T?cells isolated from BALB/c mice into syngeneic nude mice intravenously. Platelet count, proportion of reticulated platelets, platelet-associated IgG, platelet-associated anti-platelet antibodies, and IgG anti-platelet antibody production in splenocyte cultures were examined by flow cytometry. Of 69 Treg-deficient mice, 25 (36%) spontaneously developed thrombocytopenia that lasted at least 5 weeks. The platelet-associated IgG level and proportion of reticulated platelets were elevated in the thrombocytopenic mice. Platelet eluates and splenocyte culture supernatants prepared from thrombocytopenic mice, but not from nonthrombocytopenic mice, contained IgG antibodies capable of binding to intact platelets. Simultaneous transfer of Tregs completely prevented the onset of thrombocytopenia, but Treg transfer after the onset of thrombocytopenia had no apparent effect. Treatment with IgG anti-cytotoxic T?lymphocyte-associated antigen 4 antibody canceled this Treg-governed suppressive effect.?In summary, these results indicate that Tregs play a critical role in preventing murine autoantibody-mediated thrombocytopenia by engaging cytotoxic T lymphocyte-associated antigen?4.     

Thrombocytopenic purpura in narcotics addicts

Since November 1982 we have seen an association of thrombocytopenic purpura with chronic narcotic addiction in 70 patients with a mean platelet count of 53000 +/- 4000 (SE); 33 had stopped taking intravenous drugs for an average of 21.2 +/- 4.7 months; 13 of 15 had elevated antibody titers for a virus related to the acquired immunodeficiency syndrome. Platelet-bound IgG, IgM, and complement levels were 16.7-, 5.6-, and 3.1-fold greater than control values, respectively, and 2.6-, 1.9-, and 2.4-fold greater than values in 25 patients with classic autoimmune thrombocytopenic purpura studied at the same time. Thirty-three of thirty-six addicts had elevated circulating immune complexes, whereas 8 patients with autoimmune thrombocytopenia had no elevation. Eleven of eighteen addicts had positive serum platelet-reactive IgG titers, compared to 5 of 19 patients with classic autoimmune thrombocytopenia. The platelet-reactive IgG in sera of addicts was composed of 7S IgG antibody as well as high molecular weight (immune complex) IgG. Thus, chronic addicts appear to have a new immunologic platelet disorder associated with the presence of 7S IgG antiplatelet antibody, like patients with classic autoimmune thrombocytopenic purpura, and immune complex associated nonspecific platelet IgG, like male homosexual patients with thrombocytopenia.     

Autoantibodies against platelet glycoproteins in critically ill patients with thrombocytopenia

PURPOSE: The aim of the study was to investigate immunologic causes of thrombocytopenia in critically ill patients, especially causes that were related to platelet-associated IgG antibodies. SUBJECTS AND METHODS: All patients admitted to two intensive care units between May 1 and October 30, 1997, who developed thrombocytopenia (less than 100 x 10(9) platelets/L) were studied prospectively. We measured platelet-associated IgG with a radioimmunoassay using I(125)-labeled polyclonal antihuman IgG. Characterization of platelet-associated IgG was assessed with a monoclonal antibody immobilization of platelet antigen. Circulating immune complexes were also assayed. RESULTS: Of the 61 patients with thrombocytopenia, elevated platelet-associated IgG was found in 18 (30%). Associated antiplatelet autoantibodies (glycoprotein IIb/IIIa) were detected in 4 patients, circulating autoantibodies (glycoprotein Ib/IX) were detected in sera from 2 patients, and circulating immune complexes were detected in 3 patients. The nature of the platelet-associated IgG could not be determined in 10 patients. Elevated platelet-associated IgG was associated with sepsis and previous cardiopulmonary bypass. Thrombocytopenic patients with elevated platelet-associated IgG had a lower nadir platelet count (58 +/- 27 x 10(9)/L vs 74 +/- 24 x 10(9)/L, P = 0.03). CONCLUSION: Elevated platelet-associated IgG, some of which are platelet autoantibodies, is frequent in thrombocytopenic patients with sepsis or after cardiopulmonary bypass.     

Immune thrombocytopenia and Gaucher's disease

A 35-year-old Ashkenazi woman with Gaucher's disease was evaluated for persistent thrombocytopenia. The diagnosis of Gaucher's disease was made by bone marrow aspiration and confirmed by the determination of glucocerebrosidase levels in leukocytes and cultured skin fibroblasts. Studies of platelet-associated IgG and in vivo platelet survival demonstrated immune-mediated destruction of platelets consistent with immune thrombocytopenic purpura. A trial of prednisone had no effect on the platelet count. Total splenectomy resulted in a complete and prolonged remission. The clinical implications of Gaucher's disease and concurrent immune thrombocytopenic purpura are discussed.     

Platelet surface-bound IgG in patients with immune and nonimmune thrombocytopenia

We quantitated the amount of platelet surface-bound IgG using an 125I monoclonal anti-IgG assay in 149 patients with thrombocytopenia and 260 normal donors. The normal subjects had 122 +/- 5 molecules of IgG/platelet (mean +/- SE). Fifty-five patients with nonimmune thrombocytopenia had 338 +/- 37 molecules of IgG/platelet, whereas 67 patients with immune thrombocytopenia studied at the time of their initial evaluation had 4,120 +/- 494 molecules of IgG/platelet. An analysis of the distribution of values in these two groups indicated that 90% of the patients with immune thrombocytopenia had greater than 800 molecules of IgG/platelet, whereas only 7% of patients with nonimmune thrombocytopenia exceeded this amount. The immune thrombocytopenia patients included 39 idiopathic, 14 secondary, and 14 drug-induced disorders, and they did not significantly differ in their distribution of values for platelet IgG. The nonimmune thrombocytopenic patients included 12 cases with a platelet destructive mechanism; their platelet-bound IgG was similar to that of the other nonimmune patients. Twenty-seven patients with treatment resistant immune thrombocytopenia were also studied they had 2,100 +/- 670 molecules of IgG/platelet. Their values were significantly greater than those of the nonimmune thrombocytopenic patients and not significantly different from those of immune thrombocytopenic group. Their distribution of values was much broader, however, with 33% of patients having less than 800 molecules of IgG/platelet, suggesting possible alternate mechanisms in their thrombocytopenia. Thus, patients with immune thrombocytopenia have a high frequency of elevated IgG on the platelet surface which reflects the pathophysiology of this disorder. Quantitation of platelet-bound IgG provides a useful laboratory tool in the differential between immune and nonimmune thrombocytopenia.     

Thrombocytopenia caused by the development of antibodies to thrombopoietin.

Thrombocytopenia developed in some individuals treated with a recombinant thrombopoietin (TPO), pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF). Three of the subjects who developed severe thrombocytopenia were analyzed in detail to determine the cause of their thrombocytopenia. Except for easy bruising and heavy menses, none of these subjects had major bleeding episodes; none responded to intravenous immunoglobulin or prednisone. Bone marrow examination revealed a marked reduction in megakaryocytes. All 3 thrombocytopenic subjects had antibody to PEG-rHuMGDF that cross-reacted with endogenous TPO and neutralized its biological activity. All anti-TPO antibodies were immunoglobulin G (IgG), with increased amounts of IgG4; no IgM antibodies to TPO were detected at any time. A quantitative assay for IgG antibody to TPO was developed and showed that the antibody concentration varied inversely with the platelet count. Anti-TPO antibody recognized epitopes located in the first 163 amino acids of TPO and prevented TPO from binding to its receptor. In 2 subjects, endogenous TPO levels were elevated, but the TPO circulated as a biologically inactive immune complex with anti-TPO IgG; the endogenous TPO in these complexes had an apparent molecular weight of 95 000, slightly larger than the full-length recombinant TPO. None of the subjects had atypical HLA or platelet antigens, and the TPO cDNA was normal in both that were sequenced. Treatment of one subject with cyclosporine eliminated the antibody and normalized the platelet count. These data demonstrate a new mechanism for thrombocytopenia in which antibody develops to TPO; because endogenous TPO is produced constitutively, thrombocytopenia ensues.     

Auranofin or D-penicillamine in the treatment of rheumatoid arthritis

Ninety patients were entered into a randomized, controlled, double-blind trial lasting 12 months to compare auranofin (6 mg/d), and D-penicillamine (250 mg/d for 4 weeks, 500 mg/d for 4 weeks, then 750 mg/d thereafter) in the treatment of rheumatoid arthritis. Most patients in both groups completed the trial with significant improvement in all quantitative measures of efficacy. Patients treated with D-penicillamine were more likely to have "important improvement" in physician global assessment, swollen joint count, and score and grip strength. The overall frequency of side effects was similar between the two groups; however, more patients were withdrawn for adverse effects from the D-penicillamine group, and proteinuria (greater than or equal to 2+) and thrombocytopenia (less than 100 000 mm3) occurred significantly more frequently with D-penicillamine than auranofin (p = 0.028). These results suggest that in the dosage regimen used, auranofin is safer than D-penicillamine but that D-penicillamine tends to show greater clinical effectiveness in patients with rheumatoid arthritis.     

Correlation of a quinidine-induced platelet-specific antibody with development of thrombocytopenia

The rapidity by which drug-dependent antiplatelet antibodies can develop is not known, since patients are only studied during or after the episode of thrombocytopenia. This report describes the development of quinidine-induced immune thrombocytopenia in a healthy volunteer during a drug study. The thrombocytopenia developed within two weeks of initiation of quinidine therapy. During the thrombocytopenic episode, but not before receiving the drug, the patient had an IgG antiplatelet antibody that bound to control platelets in the absence of the drug. This antibody was absent when the drug was discontinued and the platelet count rose. The patient's acute serum also induced the release of serotonin from control platelets, and the reaction was enhanced by quinidine. This indicates that drug-dependent antiplatelet antibodies can develop rapidly and supports the hypothesis that quinidine-induced thrombocytopenia is due to a quinidine-dependent platelet-specific IgG.     

Quantitation of platelet-associated IgG by radial immunodiffusion

Platelet-associated IgG (PAIgG) was measured by a simple radial immunodiffusion technique using washed solubilized platelets and commercially available immunoplates. Subjects with normal platelet counts had PAIgG levels of 1.5--7.0 fg/platelet. Subjects with idiopathic immune thrombocytopenic purpura (ITP) had levels ranging from 5.7 to 70.5 fg/platelet. All patients with recurrent ITP and 85% of patients with acute ITP had elevated PAIgg. Elevated PAIgG was also found in 17% of patients with recovered ITP, 40% of patients with SLE and thrombocytopenia, 57% of patients with thrombocytopenia occurring during the course of septicemia, and 100% of patients with IgG myeloma in whom the serum IgG level was clearly elevated, regardless of the platelet count. The results are similar to reports that used more complex techniques.     

Measurement of platelet-associated IgG in animal models of immune and nonimmune thrombocytopenia

Platelet-associated IgG (PAIgG) is elevated in idiopathic thrombocytopenic purpura (ITP), but it also is elevated in other thrombocytopenic disorders traditionally considered to be nonimmune. Consequently it is possible that elevated PAIgG is a nonspecific finding secondary to thrombocytopenia. To study this issue we developed a rabbit model of immune and nonimmune mediated thrombocytopenia. The mechanism of the thrombocytopenia was validated by platelet survival studies. Immune thrombocytopenia was produced by injection of antirabbit platelet serum that was raised in guinea pigs. Nonimmune aregenerative thrombocytopenia was produced by irradiation of the animals; nonimmune consumptive thrombocytopenia was produced by injection of adenosine diphosphate (ADP). PAIgG was measured in a direct binding assay using 125I-labeled staphylococcal protein A (SpA). Washed platelets from normal, nonthrombocytopenic rabbits bound an average of 81 molecules of SpA per platelet (81 +/- 168, mean +/- 2 SD, n = 39). Infusion of the antiplatelet antiserum produced thrombocytopenia with a rise in PAIgG that was closely correlated with the level of PAIgG (r = 0.86, n = 12). The thrombocytopenia was consumptive, as shown by a very short platelet life span using 111In- labeled platelets. In contrast, both nonimmune thrombocytopenic states resulted in an equal or greater drop in the platelet count but no change in the level of PAIgG. The animals with aregenerative thrombocytopenia had normal or only moderately reduced platelet life spans; however, in every animal the level of PAIgG was not different from the nonthrombocytopenic controls, irrespective of the platelet count. Similarly, the level of PAIgG was unchanged in those rabbits with nonimmune consumptive thrombocytopenia following infusion of ADP (82 +/- 55 molecules of SpA per platelet, mean +/- SD, n = 6). These studies indicate that elevated PAIgG is a specific finding of immune thrombocytopenia and is not secondary to thrombocytopenia itself. Indirectly these results support our hypothesis that immune mechanisms contribute to more thrombocytopenic disorders than was once thought likely.     

Immune thrombocytopenia and response to splenectomy in chronic liver disease

Six patients had chronic liver diseases of diverse origin, persistent unexplained thrombocytopenia, and no palpable splenic enlargement. Platelet-associated IgG levels were increased in all cases. Two patients underwent splenectomy; the spleens weighed 375 and 230 g. Each patient had prompt, complete, and sustained platelet count normalization. Two other patients treated briefly with prednisone had no response. These observations indicate that a minimally enlarged spleen may be responsible for thrombocytopenia in chronic liver disease and suggest that immune mechanisms may contribute to thrombocytopenia in this setting.