Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 40-1998. A 49-year-old woman with thrombotic thrombocytopenic purpura and severe dyspnea during plasmapheresis and transfusion

Dyspnoea after antiplatelet agents: the AZD6140 controversy

Recent randomised studies suggest that experimental oral reversible platelet P2Y12 receptor inhibitor, AZD6140, causes dyspnoea. This also raises similar concerns about the parent compound, and another adenosine triphosphate (ATP) analogue (AR-69931MX or cangrelor), which is currently in Phase 3 trial in patients undergoing coronary interventions. We analysed package inserts, and available clinical trials safety data for antiplatelet agents with regard to the incidence of dyspnoea. We found that dyspnoea is a very rare complication of the presently approved platelet inhibitors, mostly caused by underlying disease, rather than antiplatelet therapy per se. The main reasons for respiratory distress after oral (AZD6140), and intravenous (cangrelor) agents may be the development of mild asymptomatic thrombotic thrombocytopenic purpura, fluid retention and dyspnoea because of the reversible nature of these drugs. Also, these agents are ATP analogues, which rapidly metabolise to adenosine, a well-known bronchoprovocator causing dyspnoea as well. In summary, dyspnoea is seldom considered, there are no treatment algorithms when it does occur, plausible mechanisms exist and despite these plausible mechanisms, the true cause of dyspnoea in these exposed individuals is unknown. Additional pulmonary function testing, immunological investigations and platelet receptor studies are urgently needed to determine the cause of dyspnoea after AZD6140, and to point out how such serious adverse reactions can be prevented, or at least minimised, raising potential concerns about this drug.

Optimization of a myeloid cell transfusion strategy for infected neutropenic hosts

Although granulocyte transfusion is a logical, therapeutic option for neutropenic patients with refractory infections, significant technical barriers have prevented its widespread use. A novel phagocyte transfusion strategy has been developed based on activation of a human myeloid cell line HL-60. To further define the potential for HL-60 cells to recapitulate white cell transfusions, a shortened duration of activation was evaluated, facile quality control markers were defined, and the impact of low-dose irradiation on cell function was determined. Three days of activation resulted in increased cell viability and in vitro candidacidal capacity but with slightly higher cell replication compared with 7 days of activation. Cell viability and several flow cytometric measurements were accurate, quality control markers for HL-60 activation. In combination with activation, low-dose irradiation abrogated replication while sparing the candidacidal effects of the HL-60 cells. Infusion of irradiated, activated HL-60 cells improved survival of neutropenic, candidemic mice significantly. In summary, activated, irradiated HL-60 cells are microbicidal, have virtually no replicative capacity, and are safe and effective at protecting neutropenic mice against an otherwise 100% fatal candidal infection. With continued development, this strategy to recapitulate neutrophil functions has the potential to serve as an effective alternative to granulocyte transfusions.

A phagocytic cell line markedly improves survival of infected neutropenic mice

Disseminated candidiasis is a frequent infection in neutropenic patients, in whom it causes 50% mortality, despite antifungal therapy. As the duration of neutropenia is the strongest predictor of survival in neutropenic patients with invasive fungal infections, neutrophil transfusions are a logical, therapeutic option. However, significant technical barriers have prevented the clinical use of neutrophil transfusions. To overcome these barriers, we identified a human phagocytic cell line that could be administered to candidemic hosts in lieu of freshly harvested neutrophils. HL-60 cells killed Candida albicans in vitro. Activation of HL-60 cells with dimethyl sulfoxide and retinoic acid abrogated the cells' proliferation and augmented their killing of C. albicans. Administration of activated HL-60 cells to candidemic, neutropenic mice significantly improved survival (53% vs. 0%). Live HL-60 cells chemotaxed to sites of infection, phagocytized C. albicans, and reduced the fungal burden in key target organs. Although unactivated HL-60 cells also reduced tissue fungal burden in vivo, they did not improve survival as a result of their toxicity in infected mice. In contrast, no toxicity as a result of activated HL-60 cells was observed at up to 2 months of follow-up. To our knowledge, this is the first description of a cell line-based immunotherapy for an infectious disease. With further refinements, activated HL-60 cells have the potential to overcome the technical barriers to neutrophil transfusions.

Nine Years of Cascade Filtration for Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) continues to attract physicians' attention because of its unpredictable course and underlying pathogenetic mechanisms. It is also attractive because of its optimal response to therapeutic plasma exchange (PE) even in the most severe cases. The usual approach to its treatment is conventional PE with plasma substitution and only recently fresh frozen plasma (FFP) has been substituted by cryodepleted or virally inactivated plasma with clinical results that are, if not better, at least comparable with the ones attained when FFP is employed. Nonetheless, no consensus exists regarding the optimal PE fluid and this is not of marginal interest as even after PE treatment mortality is still from 15 to 20%. On the contrary, some consensus exists on the pathogenetic relevance of the exceedingly large Von Willebrand (vWF) multimers whose presence parallels the clinical course and appears to be determined by the abnormalities in the production or function and survival of vWF-cleaving proteases which is auto-antibody mediated. In both cases plasmapheresis without plasma infusion is relatively ineffective, perhaps because it does not increase protease activity. Paradoxically, cascade filtration (CF) can produce the same favorable results without replacing any protease activity. As with CF, the replacement is the autologous plasma with approximately 20% levels of vWF, fibrinogen, fibronectin, IgM and circulating immune complexes and 75% of albumin, IgGs, AT III and proteins whose molecular weight exceeds 250-300000 Da. Our experience with CF for TTP began in 1994. Since then, 16 patients have undergone CF combined with decreasing amounts of FFP supplementation and since 1998 without any allogeneic FFP supplementation in 9 cases. Twenty-four patients (96%) treated with no or minimal amounts of FFP survived but four (16%) experienced from one to four recurrences associated with cutaneous, paradental, cholecystic and vaginal infections. Only one patient died (5%) after the second CF procedure. There were no untoward effects related to the procedure itself and up to 18 procedures in one patient were carried out over 16 months, 10 with the patient in her sixth month of pregnancy and four in the post partum period in preparation for a splenectomy. Remission was achieved after an average number of treatments (10.7 +/- 6.8); a result that compares favorably with those of our historical control group of 47 cases (14 +/- 13). The patient's exposure to allogenic plasma which was 10.8 +/- 4.6 plasma U/session was reduced to 0 in 10 patients, to 1.4 +/- 1.2 and 4.4 +/- 2.3 plasma U/session, respectively, for seven and nine patients receiving PE + CF and CF with same plasma supplementation as described in our previous article. Based on our experience, we believe CF is presently the optimal treatment for patients with classic, sporadic TTP.

Transfusion-related acute lung injury during plasma exchange: Suspecting the unsuspected

Transfusion-related acute lung injury (TRALI) has been implicated with use of almost all types of blood products that contain variable amounts of plasma. Even though the reported incidence of TRALI is rare, its overall occurrence is thought to be more common, as less severe cases remain unreported. More TRALI cases are unrecognized and misdiagnosed due to lack of suspicion and absence of appropriate investigation. There are exceedingly rare reports of TRALI during plasma exchange despite the fact that liters of plasma may be used for replacement during a single procedure. We describe a mild case of TRALI during plasma exchange for thrombotic thrombocytopenic purpura in a 56-year-old woman, status post autologous hematopoietic stem cell transplant for non-Hodgkin's lymphoma. She developed severe rigors, peripheral cyanosis, hypoxia, and a transient diffuse pulmonary infiltrate. Of the 10 U of plasma used, one was from a multiparous female donor with HLA antibodies reactive with patient's granulocytes in immunofluorescence and agglutination assays. This case emphasizes the fact that the physicians and apheresis staff should consider TRALI in the differential diagnosis for patients developing respiratory distress during or soon after the procedure. Diagnosing TRALI has implications not only for the plasma exchange recipient, but also for the management of donors found to have leukocyte antibodies.

Difficulties in the management of an incomplete form of refractory thrombotic thrombocytopenic purpura, the usefulness of vincristine

BACKGROUND

Although several etiologies can be identified in thrombotic thrombocytopenic purpura (TTP), idiopathic cases are still frequent. Incomplete forms are more rare. Currently, the diagnosis may be made in cases of thrombocytopenia and microangiopathic hemolytic anemia. According to the literature, mortality and morbidity are significantly improved with plasma exchange. However, treatment in refractory forms remains problematic.

CASE REPORT

A 33-year old woman presented with an incomplete form of TTP, refractory to a combination of therapeutics. The patient underwent plasma infusion, plasma exchange, and then was started on corticosteroids. She also received intravenous immunoglobulins and antiplatelet agents in close proximity to vincristine (Oncovin) infusion. The main biological indicators used were the platelet count, hematocrit, LDH, and the presence of schistocytes. Following vincristine treatment, the patient's condition rapidly improved.

CONCLUSION

Vincristine administered after the failure of standard therapeutics was effective in this refractory form of TTP.

Complications of plasma exchange in 71 consecutive patients treated for clinically suspected thrombotic thrombocytopenic purpura-hemolytic-uremic syndrome

BACKGROUND

With the increased frequency of diagnosis and improved survival of thrombotic thrombocytopenic purpura-hemolytic-uremic syndrome (TTP-HUS), the morbidity of plasma exchange (PE) treatment has become more important.

STUDY DESIGN AND METHODS

Data were prospectively collected on 71 consecutive patients referred to the Oklahoma Blood Institute (OBI) for PE treatment for clinically suspected TTP-HUS from mid-1996 to mid-1999. Complications were defined as major or minor, and distinguished between those related to central venous catheter access or to the plasma.

RESULTS

Twenty-one patients (30%) had 27 major complications, which caused two deaths. The major complications included 2 episodes of hemorrhage after subclavian line insertion (1 death), 1 pneumothorax requiring a chest tube, 12 systemic infections (1 death), 7 episodes of catheter thrombosis requiring removal of the central venous catheter, 2 episodes of venous thrombosis requiring anticoagulant treatment, 2 episodes of hypoxemia and hypotension, and 1 episode of serum sickness. Minor complications occurred in 22 additional patients (31%). Twenty-eight patients (39%) had no complications.

CONCLUSIONS

The morbidity and mortality of catheter placement and PE are important considerations when PE treatment for clinically suspected TTP-HUS is anticipated.

Cascade filtration for TTP: an effective alternative to plasma exchange with cryodepleted plasma

TTP remains enigmatic both in terms of etiology and management. The most recent approach is aggressive plasma exchange (PE) employing cryopoor plasma for replacement, based on the pathogenetic relevance given to exceedingly large Von Willebrand (VWF) multimers in the determination of the syndrome with normalization during remission. PE with fresh frozen plasma (FFP) is better than FFP infusion as shown by a recent Canadian study, supporting the theory that to treat TTP an offending circulating agent needs to be removed from the patient's plasma in contrast to the hypothesis that a missing factor is to be given along with FFP. A more recent hypothesis is supported by the results of studies published by the end of 1998 [Moake J, Chintagumpala M, Turner N et al. Blood 1994;84:490-97; Moake J, McPherson PD. Am J Med 1989;87: 3-9N] which would show that TTP is mediated by auto-antibodies to VWF-cleaving protease, or is the result of deficiency of the protease ascribed to abnormalities in its production, function or survival. Plasmapheresis without plasma infusion is relatively ineffective perhaps because it does not increase the protease activity. Cascade filtration (CF) is the autologous counterpart of plasmapheresis. It has been used by our group since 1980 to remove from patients plasma macromolecules such as VWF, fibrinogen, LDL and circulatory immune complexes (CIC). After secondary filtration, the autologous plasma has a composition which is very similar to that of allogeneic plasma after cryoprecipitation, a product which used in the management of TTP. Based on this knowledge, in 1994 we began to use CF in the treatment of TTP patients. In the beginning (7 patients) CF was combined with a decreasing number of conventional PEs using allogeneic plasma for substitution. Lately only CF with some plasma supplementation has been used in the last 9 cases. From a clinical point of view our 16 patients achieved remission after a number of treatments (11 +/- 7) that compares sufficiently well with those required by our historical control group of 47 cases (14 +/- 13). Of course the patient's exposure to allogenic plasma was significantly lower for patients in the CF only group (1.4 +/- 1.2 plasma U/session) compared to the PE + CF group (4.4 +/- 2.3 plasma U/session) or for the controls treated by PE only (10.8 +/- 4.6 plasma U/session). There were no deaths in the CF or PE + CF groups and no untoward effect was observed. On the contrary there were 5 deaths (1 on the day of presentation) in the PE group, and 1 HBV and 2 HCV infections as well as 4 severe allergic reactions to plasma proteins (or passive antibody infusion). We conclude that CF is presently the best treatment to offer to patients suffering from sporadic TTP and that CF may contribute to expanding the knowledge of the pathogenetic mechanisms of this uncommon multisystem disorder.