Plateletpheresis with the IBM Model 2997

Abstract. 9 healthy subjects dosed with acid-citrate-dextrose, NIH formula B (ACD-B) while undergoing plateletpheresis with the continuous-flow IBM Model 2997 centrifuge, received on average 59.5 ± (SD) 3.2 mg Na₃ citrate-kg^-1. h^-1. This rate of infusion of Na₃ citrate resulted in a maximum 12-fold rise in the concentration of citrate in serum (plasma) following the processing of 10 litres of whole blood, and subsequently reduced the level of total calcium in serum (plasma) by 9%. This dose of Na₃ citrate produced no clinical symptoms suggestive of hypocalcaemia in these subjects, even though the use of acid-citrate-dextrose, NIH formula A (ACD-A) under identical conditions has been reported to reduce significantly the level of total calcium in serum, and concomitantly increase the number or reactions occurring in donors. From previous studies employing the intermittent-flow centrifugation system of plateletpheresis, a rate of infusion of Na₃ citrate below 65 mg.kg^-1. h^-1 can insure maximum donor safety and this rate can be achieved with the IBM Model 2997 by the utilisation of ACD-B.     

Evaluation of the Use of a Platelet-Counting Tool in Plateletpheresis

OBJECTIVE: For years, blood transfusion centers in Taiwan have used the Quantitative Buffy Coat (QBC(R)) Hematology System for platelet counts on capillary blood samples in the laboratory screening of apheresis donors. The system has not been evaluated for the prediction of yields in plateletpheresis. Methods : The QBC instrument was evaluated for reproducibility of platelet counts and compared with five electronic cell counters. We also collected both capillary and venous blood from voluntary donors before donation and counted platelets, comparing the QBC system and an electronic blood cell counter (Sysmex K1000). The correlation between donors' predonation platelet counts and plateletpheresis yields was analyzed. RESULTS: The R values for platelet counts between the QBC Hematology System and other electronic counters are lower (0.759-0. 890) than among the electronic counters (0.929-0.973). The mean capillary platelet count and the mean venous platelet count were 241. 9+/-50.3x10(3)/microl and 233.2 +/-47.9x10(3)/microl by the QBC system, and 244.9+/-54.1x10(3)/microl and 218.9+/-46.5x10(3)/microl by the Sysmex K1000, respectively. Linear regression analysis showed that platelet yields correlated well with donors' predonation platelet counts using the Sysmex K1000 counter (R = 0.777- 0.890, p<0.001), but not with the QBC system (R = 0.326 approximately 0.755, p<0.05). CONCLUSION: The QBC Hematology System is not accurate enough to determine predonation platelet counts that are to be used for calculating the number of processing cycles for plateletpheresis.     

Plateletpheresis Using the Haemonetics Model 30 Cell Separator

Abstract. Plateletpheresis using the Haemonetics Model 30® cell separator results in a mean collection of 5.5 × 10¹¹ platelets. This product contains substantial numbers of erythrocytes and mononuclear cells which can be effectively removed by centrifugation but with a 23% loss of platelets as well. The mean decrement in donor's platelet count during the procedure, which is 78,000/mm³, is not commensurate with the number of platelets collected suggesting donor platelet mobilization. Platelets collected by this technic, when transfused into unselected recipients, give platelet increments comparable to platelets produced in the standard batch manner.     

Familial thrombocytosis

Four cases of thrombocytosis in three successive generations of a family are described. High peripheral platelet count was found incidentally in the proband with cutaneous malignant lymphoma. Bone marrow examination showed megakaryocytic hyperplasia. Neither Philadephia chromosome nor chimaeric bcr/abl junction was detected in marrow cells. In this family, thrombocytosis was thought to be transmitted by an autosomal dominant mode of inheritance.     

Primary thrombocytosis in children

Myeloproliferative neoplasms are uncommon disorders in children, for which we have limited understanding of the pathogenesis and optimal management. JAK2 and MPL mutations, while common drivers of myeloproliferative neoplasms in adult patients, are not clearly linked to pediatric disease. Management and clinical outcomes in adults have been well delineated with defined recommendations for risk stratification and treatment. This is not the case for pediatric patients, for whom there is neither a standard approach to workup nor any consensus regarding management. This review will discuss thrombocytosis in children, including causes of thrombocytosis in children, the limited knowledge we have regarding pediatric primary thrombocytosis, and our thoughts on potential risk stratification and management, and future questions to be answered by laboratory research and collaborative clinical study.     

Platelet glyoxalases in thrombocytosis

In platelets of patients suffering from thrombocytosis due to myeloproliferative disorders, glyoxalase I activity is significantly higher than in controls (P less than 0.01), while glyoxalase II levels are the same (P less than 0.3). The cellular concentration of glutathione is also increased in patients. Km values for methylglyoxal (glyoxalase I) and S-lactoylglutathione (glyoxalase II) are identical both in normal and pathological subjects, as are the thermostability of the two enzymes. The higher activity observed for glyoxalase I in patients could be related to a specific role of this enzyme in platelets.     

Analysis of Pre- and Post-Donation Haematological Values in Plateletpheresis Donors

Pre- and post-donation haematological values were measured in 112 donors undergoing plateletpheresis using Haemonetics PCS machines. We found significant differences between pre- and post-donation means for males (M) and females (F) for haemoglobin (M: pre 14.73 g/dl, post 15.25 g/dl; F: pre 13.57 g/dl, post 13.94 g/dl), haematocrit (M: pre 0.418, post 0.431; F: pre 0.389, post 0.4), total protein (M: pre 73.1 g/1, post 66 g/1; F: pre 72.2 g/1, post 63.7 g/1) and albumin (M: pre 42.2 g/1, post 38.5 g/1; F: 41.4 g/1, post 37 g/1). Significant differences were also seen for platelet count (pre 258.6 times 10⁹/1, post 229.2 times 10⁹/1), total white cells (pre 5.3 times 10⁹/1, post 5.55 times 10⁹/1) and neutrophils (pre 3.15 times 10⁹/1, post 3.33 times 10⁹/1), but there were no differences between males and females. This information was of value in establishing post-donation reference ranges which could be utilised when reviewing the suitability of donors for subsequent donations.     

Which tests are most useful in distinguishing between reactive thrombocytosis and the thrombocytosis of myeloproliferative disease?

In an attempt to distinguish between thrombocytosis in myeloproliferative disease (MPD) and reactive thrombocytosis (RT) the following aspects of platelet structure and function were evaluated: platelet size, platelet aggregation and adhesion, dense granule and alpha granule components. In addition plasma fibrinogen and von Willebrand factor antigen (vWFag) were measured. In all parameters measured there was a significant difference between normals and both categories of thrombocytosis, however there was considerable overlap between MPD and RT. Plasma fibrinogen emerged as the best single test to discriminate between MPD and RT, levels of less than 5.0 g/l indicating MPD and greater than 5.0 g/l indicating RT.     

Repeat Plateletpheresis: The Effects on the Donor and the Yield

Requirements for HLA ot otherwise matched single-donor platelets may sometimes require repeat plateletpheresis of an individual donor. AABB standards permit the repeat collection of platelets by plateletpheresis of a single donor at 48-hour intervals, whereas recent recommendations from England state that a donor should not donate platelets more often than 12 times a year. To assess the effects of repeat plateletpheresis on the donor, we have studied the hematological indices and the product yields following every other day plateletpheresis of 13 normal donors who gave a total of 10 times during 22 days. The platelet count decreased in every case, with the lowest values reached at the third donation (day 5). The pre-donation count averaged 225 +/- 53 x 10(9)/l decreasing to 174 +/- 27 x 10(9)/l at the time of the 3rd donation then increasing by the 6th donation to 198 +/- 46 x 10(9)/l. The yield in the product decreased from 3.2 +/- 1.3 x 10(11) on day 1 to 2.6 +/- 0.8 x 10(11) for the third donation, returning thereafter to higher values. In spite of the expected and apparent stimulation of platelet production through feedback, the counts did not rebound above starting levels indicating a basic homeostatic mechanism. The donor WBC showed minimal changes during the study period, however there was a significant increase in the total number of lymphocytes by the 3rd procedure; this was corrected by the fifth procedure. The absolute number and ratio of T4 (helper) and T8 (suppressor) lymphocytes did not change.(ABSTRACT TRUNCATED AT 250 WORDS)     

Guideline for investigation and management of adults and children presenting with a thrombocytosis

Acute lymphoblastic leukaemia (ALL) remains the most frequent cause of cancer‐related mortality in paediatrics and outcome is poor for patients who have high‐risk ALL or relapse. HA22 (CAT‐8015) is an immunotoxin composed of an anti‐CD22 variable fragment linked to a 38 kDa truncated protein derived from Pseudomonas exotoxin A. Using a bone marrow mesenchymal cell culture assay to support ALL cell viability, we investigated the in vitro cytotoxicity of HA22 against ALL blasts from newly diagnosed (n = 13) and relapsed patients (n = 22). There was interpatient variability in sensitivity to HA22. Twenty‐four of 35 patient samples tested were sensitive (median 50% lethal concentration 3 ng/ml, range 1–80 ng/ml). Blasts from the other 11 patients were not killed by 500 ng/ml HA22. The median 50% lethal concentration was 20 ng/ml for all patients. There was no significant difference in HA22 sensitivity between diagnosis and relapse samples but peripheral blood ALL blasts were more sensitive to HA22 than those from bone marrow (P = 0·008). Thus, HA22, at concentrations achievable in patients, is highly cytotoxic to B‐lineage ALL cells. These results provide a strong rationale for clinical testing of this agent in children with drug‐resistant ALL and offers the potential to reduce morbidities of treatment while improving outcome.     

Paraneoplastic thrombocytosis in gastrointestinal cancer

It has been demonstrated recently in several solid tumors that thrombocytosis at diagnosis may correlate with tumor invasion, metastatic progression and worse outcome. Several details of the pathomechanism of the relationship of thrombocytosis and cancer have been elucidated; however, the complete process is not clearly understood. Several hypotheses have been proposed. Recently, it was suggested that in ovarian cancer elevated IL-6 production by the tumor may induce increased megakaryopoiesis via hepatic thrombopoietin production leading to thrombocytosis. The importance of the prognostic power of elevated platelet count is still debated in gastrointestinal cancer. The aims of this review were to evaluate the prognostic significance of thrombocytosis in gastrointestinal tumors, to see whether clinical practice confirmed the hypotheses and to reveal the causes of the inconsistent findings.     

Benign familial thrombocytosis

A 13-year-old girl was found to have a platelet count in excess of 4 million/microliters while being evaluated for a minor bleeding episode. Her father and two sisters also had thrombocytosis. All four affected patients were asymptomatic and had no clinical or laboratory evidence of a myeloproliferative disorder other than an elevated platelet count. This represents the second reported instance of benign familial thrombocytosis.     

The Play of Citrate Infusion with Calcium in Plateletpheresis Donors

Citrate is the anticoagulant of choice for plateletpheresis. Citrate toxicity is common during plateletpheresis as citrate chelates calcium and causes hypocalcemia in donors. We have conducted this study to analyze the effects of routine citrate infusion during plateletpheresis on laboratory and clinical parameters. We also compared the dose of citrate delivered to donors during plateletpheresis using two different cell separators as Haemonetics MCS + and Trima Accel. The study was conducted on 50 plateletpheresis donors who were eligible for donation. Donor demographics and baseline parameters were recorded. Pre, mid and post-procedure blood samples were collected for hematological and biochemical analysis. We found a significant decrease in baseline iCa (1.23 ± 0.07 mmol/L) from start to mid-procedure (1.19 ± 0.006 mmol/L) which recovered at 30 min post procedure (1.2 ± 0.01 mmol/L). The incidence of citrate toxicity was 10%. In donors with citrate toxicity, the post-procedure recovery of iCa was not seen and there was a further decrease in iCa levels. We also found a significant fall in Hb and platelet count post plateletpheresis. We observed that lower PLT counts (< 200 × 10³/µL) necessitated higher blood volume processing and therefore a higher anticoagulant (citrate) dose. The Trima Accel cell separator reached platelet target yield faster but with a higher citrate dose as compared to Hemonetics MCS + . Ionized calcium decreases significantly during plateletpheresis but recovers soon after the completion of the procedure. Serious adverse events were not observed during plateletpheresis. The mild citrate toxicity which occurred was easily managed by slowing the procedure and administering oral calcium to donors. Trima Accel and Hemonetics MCS + both collected platelets efficiently, with minimal donor discomfort.