Plasma exchange conditioning for ABO-incompatible renal transplantation.

The supply of deceased donor kidneys is inadequate to meet demand. To expand the pool of potential donors, ABO-incompatible transplants from living donors have been performed. We present the Mayo Clinic experience with such transplants. Enrollment was open to patients when the only available potential living kidney donor was ABO-incompatible. Conditioning consisted of plasma exchanges followed by intravenous immunoglobulin. Splenectomy was performed at the time of transplant surgery. Post-transplant immunosuppression consisted of anti-T lymphocyte antibody, tacrolimus, mycophenolate mofetil, and prednisone. Isoagglutinin titers and scores were determined before and after each plasma exchange. Transplant outcomes were determined. Twenty-six ABO-incompatible transplants were performed. No hyperacute rejection occurred. Mean patient follow-up was 400 days. Patient and graft survivals at last follow-up were 92 and 85%, respectively. Antibody-mediated rejection occurred in 46% and was apparently reversed in 83% by plasma exchange and increased immunosuppression. The initial plasma exchange reduced immediate spin and AHG hemagglutination reactivity scores by 53.5 and 34.6%, respectively. Over the course of the pretransplant plasma exchanges, the immediate spin and AHG hemagglutination reactivity scores decreased by 96.4 and 68.5%, respectively. At 3 and 12 months, the immediate spin and AHG hemagglutinin reactivity scores and titers were less than those at baseline but greater than or equal to those on the day of transplantation. Despite an increase in scores and titers, antibody-mediated rejection was not present. Pre-transplant plasma exchange conditioning combined with other immunosuppressives can be used to prepare patients for ABO-incompatible kidney transplantation from living donors, but antibody-mediated rejection post-transplant is a common occurrence and allograft survival may be reduced. Controlled clinical trials are needed to identify the optimum conditioning for ABO-incompatible renal transplants.

The dose of infused lymphocytes in the autograft directly correlates with clinical outcome after autologous peripheral blood hematopoietic stem cell transplantation in multiple myeloma.

Absolute lymphocyte count at day 15 (ALC-15) after autologous peripheral blood hematopoietic stem cell transplantation (APHSCT) is an independent prognostic factor for survival in multiple myeloma (MM); however, factors affecting ALC-15 in MM remain unknown. We hypothesized that the dose of infused peripheral blood autograft lymphocytes (autograft absolute lymphocyte count: A-ALC) impacts ALC-15 recovery. Between 1989 and 2001, 267 consecutive MM patients underwent APHSCT. We set out to determine the correlation between A-ALC and ALC-15 and the utility of A-ALC as a marker for ALC-15 recovery. A-ALC was found to be both a strong predictor for area under curve (AUC=0.93; P=0.0001) and strongly correlated with (r(s)=0.83; P=0.0001) ALC-15 recovery. Higher infused A-ALC was significantly correlated with an ALC-15>/=500/microl. In addition, median post-transplant overall survival (OS) and time to progression (TTP) were longer in patients who received an A-ALC>/=0.5 x 10(9) lymphocytes/kg versus A-ALC <0.5 x 10(9) lymphocytes/kg (58 vs 30 months, P=0.00022; 22 vs 15 months, P<0.00012, respectively). Multivariate analysis demonstrated A-ALC as an independent prognostic indicator for OS and TTP. These results indicate that an infused dose of autograft lymphocytes significantly impacts clinical outcome post-APHSCT in MM.

Infused peripheral blood autograft absolute lymphocyte count correlates with day 15 absolute lymphocyte count and clinical outcome after autologous peripheral hematopoietic stem cell transplantation in non-Hodgkin's lymphoma.

Absolute lymphocyte count at day 15 (ALC-15) after autologous peripheral blood hematopoietic stem cell transplantation (APHSCT) is an independent prognostic factor for survival in non-Hodgkin's lymphoma (NHL). Factors affecting ALC-15 remain unknown. We hypothesized that dose of infused autograft lymphocytes (A-ALC) directly impacts upon ALC-15. A total of 190 consecutive NHL patients received A-ALC between 1993 and 2001. The primary end point was correlation between A-ALC and ALC-15. A strong correlation was identified (r=0.71). A higher A-ALC was infused into patients achieving an ALC-15 > or =500/microl vs ALC-15 <500/microl (median of 0.68 x 10(9)/kg (0.04-2.21 x 10(9)/kg), vs 0.34 x 10(9)/kg (0.04-1.42 x 10(9)/kg), P<0.0001). The median follow-up for all patients was 36 months (maximum of 109 months). The A-ALC threshold was determined at 0.5 x 10(9)/kg. The median overall survival (OS) and progression-free survival (PFS) times were longer in patients who received an A-ALC >/=0.5 x 10(9)/kg vs A-ALC <0.5 x 10(9)/kg (76 vs 17 months, P<0.0001; 49 vs 10 months, P<0.0001, respectively). Multivariate analysis demonstrated A-ALC to be an independent prognostic indicator for OS and PFS. These data support our hypothesis that ALC-15 and survival are dependent upon the dose of infused A-ALC in NHL.

New directions in plasma exchange.

PURPOSE OF REVIEW: This review examines the literature published on therapeutic plasma exchange during 2002. The review was performed by searching Medline for pertinent articles. RECENT FINDINGS: One hundred thirty articles were identified, of which 11 are reviewed. During the period, reviews of the use of therapeutic plasma exchange for managing Guillain-Barré syndrome and myasthenia gravis were published. A large randomized trial of the use of plasma exchange to treat sepsis also appeared. Finally, a large case series of the use of plasma exchange in Wegener granulomatosis was published. SUMMARY: The literature confirms the use of plasma exchange for Guillain-Barré syndrome but suggests that inadequate evidence exists to support its use for long-term improvement in myasthenia gravis. The study of patients with severe sepsis suggests that plasma exchange may benefit a subset of patients, those with abdominal infections. Finally, plasma exchange for Wegener granulomatosis with severe renal dysfunction appears not to offer any benefit over immunosuppressive therapy.

Plasma exchange for severe attacks of CNS demyelination: predictors of response.

The authors reviewed 59 consecutive patients treated with plasma exchange (PE) for acute, severe attacks of CNS demyelination at Mayo Clinic from January 1984 through June 2000. Most patients had relapsing-remitting MS (n = 22, 37.3%), neuromyelitis optica (NMO) (n = 10, 16.9%), and acute disseminated encephalomyelitis (n = 10, 16.9%). PE was followed by moderate or marked functional improvement in 44.1% of treated patients. Male sex (p = 0.021), preserved reflexes (p = 0.019), and early initiation of treatment (p = 0.009) were associated with moderate or marked improvement. Successfully treated patients improved rapidly following PE, and improvement was sustained.

Therapeutic plasma exchange: a paired comparison of Fresenius AS104 vs. COBE Spectra.

For therapeutic plasma exchange (TPE), continuous flow separators are known to be efficient as exemplified by Fresenius AS104 and COBE Spectra. The AS104 uses an interface monitoring system in the centrifuge during TPE, whereas Spectra uses computer algorithms to establish the plasma-cell interface. To determine the plasma collection efficiency (PLCE), anticoagulant (AC) volumes used, and platelets (PLT) lost of the AS104 and the Spectra, we performed a prospective paired comparison of 20 TPE (each machine). The study included 17 patients, 1.3 plasma volume exchanges (without AC), equal inlet rates, and AC ratio of 13:1. Processing times did not include reinfuse mode. Platelet loss was determined by sampling the collection bags. Inlet rates were between 60-110 ml/min. Diagnosis included peripheral neuropathies, TTP and cryoglobulinemia. The AS104 had significantly (P<0.0001) lower average whole blood processed (F:6,601 vs. S:8,584 ml), AC volume (F:532 vs. S:719 ml), and processing time (F:80 vs. S:102 minutes) than Spectra. The AS104 had significantly (P<0.0001) higher average plasma flow rates (F:53 vs. S:44 ml/minute), plasma collection efficiency (F:90 vs. S:69%), and platelet loss (F:2.0 vs. S:0.14 x 10(11) plt) than Spectra. Platelet loss correlated with inlet flow rate with the AS104 but not with the Spectra. The AS104 has a significantly higher collection efficiency than Spectra allowing it to remove the same amount of plasma in significantly less time, by processing significantly less blood, using significantly less AC, but removing significantly more platelets than Spectra.

RBC alloantibody specificity and antigen potency in Olmsted County, Minnesota.

BACKGROUND: While RBC antigen frequencies for whites of Northern European ancestry are known, the relative frequencies of RBC antibodies within this population have not been determined. The distribution of RBC alloantibodies by sex and age was studied, as were the immunogenicity of RBC antigens and the occurrence of RBC alloantibody clusters in a geographically defined population. STUDY DESIGN AND METHODS: RBC alloimmunization among patients and donors in Olmsted County, MN, was determined for the period from 1975 to 1995. Alloantibody frequencies were used to calculate the potency of each antigen relative to K. Cluster analysis was applied to the data to identify natural groupings of antibodies. RESULTS: The frequency and potency of 33 alloantibodies from 1345 alloimmunized subjects were estimated. The most frequent alloantibodies were E (20.8%), Le(a) (18.6%), K (14.7%), D (12.9%), Le(b) (9.4%), M (7.2%), P(1) (6.7%), Fy(a) (6.3%), C (6.8%), and c (3.5%). The most potent antigens were Wr(a) (0.363), C(w) (0.078), Le(a) (0.03), E (0.028), V (0.025), Js(a) (0.023), Kp(b) (0.023), Go(a) (0.023), JMH (0.023), and Rd (0.023). Greater frequency of overall alloimmunization (M:F = 1:2.7), anti-D (p<0.0001), and anti-Le(a) (p = 0.003) was seen among females. Warm autoantibodies were more frequent among males with positive antibody screens (p<0.0001). No other gender differences were observed. Alloimmunization increased with age for K, Kp(a), Fy(a), D, C, E, and warm autoantibodies. Frequencies of alloimmunization to Le(a), Le(b), M, and P(1) decreased with age. The cluster analysis showed grouping of the antibodies to C and D as well as to Le(a) and Le(b), but the other RBC alloantibodies did not form clusters. CONCLUSION: Less than 1 percent of residents tested had positive antibody screens. Anti-E and anti-Le(a) were more common than anti-K. Wr(a) and C(w) were more potent antigens than K. Most antibodies showed an increase in frequency with increasing age. Except for anti-C and -D and anti-Le(a) and -Le(b), RBC alloantibodies did not occur in clusters.

Low-density lipoprotein apheresis for the treatment of refractory hyperlipidemia.

The advent of treatment with 3-hydroxy-3-methylglutaryl coenzyme A inhibitors has meant that, with a combination of diet and drug therapy, adequate control of serum cholesterol concentrations can be achieved in most patients with hypercholesterolemia. However, some patients, primarily those with familial hypercholesterolemia (FH), may require additional therapy to lower their cholesterol levels. In recent years, low-density lipoprotein (LDL) apheresis has emerged as an effective method of treatment in these patients. The criteria for commencement of LDL apheresis are LDL cholesterol levels of 500 mg/dL or higher for homozygous FH patients, 300 mg/dL or higher for heterozygous FH patients in whom medical therapy has failed, and 200 mg/dL or higher for heterozygous FH patients with documented coronary disease and in whom medical therapy has failed. In addition to cholesterol lowering in patients with FH, other indications for LDL apheresis are emerging. These include its use in the treatment of graft vascular disease in patients receiving cardiac transplants as well as in the treatment of certain glomerulonephritides. This review examines the role of LDL apheresis in the management of lipid disorders and the evidence available to support its use in clinical practice.

Autologous transfusion and other approaches to reduce allogeneic blood exposure.

When used as the sole source of transfused blood, the principal advantage of autologous blood transfusion is the avoidance of transmission of infectious agents and the avoidance of the purported adverse immunomodulatory effects of allogeneic transfusion. In the 1990s, however, the risks of transfusion-transmitted diseases have been greatly reduced, and estimates of the cost-effectiveness of pre-operative autologous blood donations now vary between 2470 dollars and 3,400,000 dollars per quality-adjusted year of life saved, depending on assumptions about the existence and magnitude of any adverse immunomodulatory effects of allogeneic transfusion. There is a paucity of randomized controlled trials evaluating the clinical outcomes and the cost-effectiveness of autologous transfusion procedures, and this situation is unlikely to change in the near future because of the difficulties in conducting such trials. This chapter reviews the available evidence on the efficacy, safety and cost-effectiveness of the three common autologous transfusion procedures, that is, pre-operative autologous blood donation, acute normovolaemic haemodilution, and intra-operative and post-operative blood recovery.

Growth of bacteria in inoculated platelets: implications for bacteria detection and the extension of platelet storage.

BACKGROUND: Recent reports from Europe have advocated the use of bacterial culturing of platelets on Day 2 or 3 of storage to extend the shelf life of platelets to 7 days, thereby reducing the outdating of platelets and preserving a limited medical resource. To assess the optimal timing, the necessary sensitivity, and the possible efficacy of bacterial detection, the bacterial growth characteristics were reviewed in 165 platelet units, each inoculated on the day of collection with one of the following organisms: Bacillus cereus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis from four previously published studies. STUDY DESIGN AND METHODS: Quantitative culture data from inoculated platelet concentrates from five sites and four studies were combined into one database and analyzed for bacterial concentration thresholds (> or =10(1), > or =10(2), > or =10(3), > or =10(4), > or =10(5) CFU/mL) by day of storage. RESULTS: All examples of B. cereus, P. aeruginosa, K. pneumoniae, S. marcescens, and S. aureus had concentrations > or =10(2) CFU per mL by Day 3 after inoculation. By Day 4, all units with these organisms contained > or =10(5) CFU per mL. Units contaminated with S. epidermidis showed slower and more varied growth. By Day 3 after inoculation, 81.3 percent had 10(2) CFU per mL. By Day 4 after inoculation, 46 (95.8%) of 48 units had concentrations > or =10(2) CFU per mL. CONCLUSION: These experiments suggest that an assay capable of detecting 10(2) CFU per mL on Day 3 of storage would detect the vast majority of bacterially contaminated platelet units, prevent many cases of platelet-associated bacterial sepsis, and provide a scientific basis for the extension of the current platelet storage time. It would be expected that a rare, slow-growing organism could escape such a detection scheme.

A randomized trial of plasma exchange in acute central nervous system inflammatory demyelinating disease.

There are no established treatments for patients with acute, severe neurological deficits caused by multiple sclerosis or other inflammatory demyelinating diseases of the central nervous system who fail to recover after treatment with high-dose corticosteroids. We conducted a randomized, sham-controlled, double-masked study of plasma exchange without concomitant immunosuppressive treatment in patients with recently acquired, severe neurological deficits resulting from attacks of inflammatory demyelinating disease, who failed to recover after treatment with intravenous corticosteroids. Patients who did not achieve moderate or greater improvement after the first treatment phase crossed over to the opposite treatment. Moderate or greater improvement in neurological disability occurred during 8 of 19 (42.1%) courses of active treatment compared with 1 of 17 (5.9%) courses of sham treatment. The primary analysis was positive. Improvement occurred early in the course of treatment, and was sustained on follow-up. However, 4 of the patients who responded to the active treatment experienced new attacks of demyelinating disease during 6 months of follow-up. Moderate or greater improvement occurred during follow-up in only 2 of 13 patients who failed to improve during the treatment phase. Plasma exchange leads to functionally important neurological recovery in an important proportion of severely disabled patients with acute attacks of idiopathic inflammatory demyelinating disease.

Prospective comparison of plateletapheresis using four apheresis systems on the same donors.

To address the demand for higher plateletapheresis efficiency while maintaining consistent leukoreduction, manufacturers of apheresis systems have introduced new equipment or modifications to existing equipment. Using the same 20 donors, we compared the Fresenius AS104 (AS104), Fenwal Amicus, and COBE Spectra Version 7 Leukoreduction System (Turbo) to the COBE Spectra Version 5 Leukoreduction System (V5-LRS) and each other in regard to platelet (plt) collection efficiencies, processing times, and leukoreduction consistency. Using current pre-procedure platelet counts, target endpoints were set at 6-6.5 x 10(11) plt or 3.3-4.0 x 10(11) plt in up to 100 minutes processing time. Median platelet yields for V5-LRS, AS104, Amicus, and Turbo were 3.98, 3.63, 5.03, and 4.99 x 10(11) plt respectively; median collection efficiencies were 53, 46, 73, and 56% respectively; median collection rates were.049,.039,.065, and. 060 x 10(11) plt/minute respectively; double product frequencies were 35, 10, 40, and 30% respectively; and median processing times were 87, 92, 77, and 79 minutes, respectively. Amicus had a significantly higher collection efficiency and higher incidence of double products than all other systems. While AS104 had a significantly lower collection efficiency and lowest double product frequency than all other systems, Amicus and Turbo had significantly lower processing times than V5-LRS and AS104. AS104 leukoreduction was inconsistent, but V5-LRS, Amicus, and Turbo were consistently leukoreduced ((99.8% had <5 x 10(6) WBC at 95% confidence interval). The best overall performance was for the Amicus with Turbo a close second.

Trends in the incidence of delayed hemolytic and delayed serologic transfusion reactions.

BACKGROUND: An increasing incidence of delayed hemolytic and delayed serologic transfusion reactions (DHTRs/DSTRs) has been seen at the Mayo Clinic since 1978. Recently, the average length of stay (LOS) for inpatients and the average number of red cell transfusions per inpatient (TPI) decreased, and the albumin and papain technique for RBC antibody detection was replaced by a polyethylene glycol technique. These changes may have affected the incidence of DHTRs/DSTRs. STUDY DESIGN AND METHODS: The diagnoses of DHTR and DSTR made at the Mayo Clinic from 1993 through 1998 were reviewed. These data were compared with previously published Mayo Clinic data from 1980 through 1992. The LOS for inpatients and the average TPI were also obtained from hospital data. RESULTS: The incidence of DHTR/DSTR increased from 1 in 1899 in 1980 through 1992 to 1 in 1300 in the 1993 through 1998 period (p < 0.05). Similarly, DSTR increased from 1 in 2990 in 1980 through 1992 to 1 in 1612 in the 1993 through 1998 period (p < 0.05). The incidence of DHTR showed a trend toward decrease, from 1 in 5405 in 1980 through 1992 to 1 in 6715 in 1993 through 1998. No alloantibody specificities were statistically associated with DHTRs in 1993 through 1998, unlike in the 1980 through 1992 period. Moreover, the incidence of Jka antibodies increased in 1993 through 1998, while the incidence of other alloantibodies remained stable. Average LOS and TPI declined by 24.5 percent and 8.8 percent, respectively, between the two periods. CONCLUSION: Recently, a trend toward a decrease in the incidence of DHTR and a significant increase in DSTRs has occurred at the Mayo Clinic. These changes are most likely due to a combination of factors, including a decrease in average LOS and the adoption of the polyethylene glycol antibody detection system.

Early harvest and late transplantation as an effective therapeutic strategy in multiple myeloma.

Transplantation after high-dose chemotherapy prolongs survival in patients with multiple myeloma compared with standard therapy. It is unclear whether the optimal timing of transplantation is immediately after induction chemotherapy or whether stem cells may be cryopreserved for transplantation at subsequent progression or relapse. In this study, stem cells were collected within 6 months of diagnosis, followed by transplantation only at progression of myeloma. One hundred and eighteen patients with multiple myeloma had stem cells collected and cryopreserved. Eleven had transplants early in the disease after they demonstrated failure to respond to primary therapy. The remaining 107 were eligible for transplants when there was evidence of progressive disease. Of the 118 patients, 67 had transplants, nine died of progressive disease before transplantation, and 42 remain alive in plateau phase. The median survival of the group is 58.5 months; 67 are alive. Serum beta2-microglobulin, bone marrow labeling index (S phase), and hemoglobin level predicted overall survival (P < 0.006, P < 0.001, and P < 0.01, respectively). We conclude that early cryopreservation of blood stem cells followed by transplantation at progression is a feasible approach to therapy in patients with myeloma. The underlying biology of the disease has a greater impact on survival than the timing of transplantation. A prospective randomized trial is required to answer definitively the question of the optimal timing of blood cell transplantation.

Plateletapheresis: instrumentation validation.

Plateletapheresis instrumentation validation is required to document that a new or modified instrument or technique is capable of consistently producing acceptable products at the production center using their equipment, personnel, and counting techniques even though the instrument or technique may already have FDA or equivalent approval for use. To pursue the process of validation, several questions need to be addressed: when is it required, what products are validated, what parameters are monitored, and how many products are required. Validation is required when a new instrument or technique (process) is used that could affect the quality of the product. According to the FDA, each apheresis system (e.g., Spectra LRS, Amicus) and each type of product (e.g., single, double, triple) need to be validated separately. Parameters to be validated vary, but usually platelet (plt) yield, white blood cell (WBC) content (if products are labeled "leukoreduced"), and 5-day storage pH are monitored. The number of procedures monitored is also quite variable, but we use 20 samples for highly variable parameters such as platelet yield and WBC content and five samples for less variable parameters such as 5-day storage pH. As an example, we validated the Fenwal Amicus (Baxter Biotech) for single apheresis platelet products. With 20 samples, we found that: 85% of the products contained > or = 3 x 10(11) plt (requirement was at least 75% contain > or = 3 x 10(11) plt); platelet concentration of all products was < or = 1.515 x 10(6) plt/microL (requirement was < or = 2.435 x 10(6) plt/microL), and WBC content was < 1 x 10(6) WBC in all products (requirement was all products contain < 5 x 10(6) WBC). In addition, in five samples, the 5-day storage pH was 6.89-7.25 (requirement was all products should be > or = 6.2 pH). Once validation is complete and acceptable, the process should be monitored on a regular basis using some form of process control. Statistical process control programs are available that can assist in documenting validation and ongoing process control. With the use of process validation and ongoing process control, the plateletapheresis center can assure that acceptable products are consistently being produced.

Factors influencing platelet recovery after blood cell transplantation in multiple myeloma.

We sought to determine factors that impact on the recovery of platelets after blood cell transplantation in patients with multiple myeloma. We performed retrospective analyses in 51 patients undergoing blood cell transplantation for multiple myeloma. The proportional-hazards model was applied to determine significant risk factors. Of 51 transplants, 14 patients failed to achieve a platelet count of 50 x 10(9)/l. Median time to a neutrophil count of 0.5 x 10(9)/l was 10.5 days. Median time to achieve a platelet count of 50 x 10(9)/l was 32 days. Multivariate analysis revealed that cyclophosphamide and G-CSF priming before collection of hematopoietic precursors (P < 0.001) was a positive predictor of rapid engraftment and prior exposure to melphalan given orally (P = 0.02) was a negative predictor of subsequent platelet engraftment. The number of mononuclear cells collected, the patient's disease status at the time of transplant and the presence of circulating plasma cells in the harvested product did not have a significant impact on time to platelet engraftment. We conclude that cyclophosphamide and G-CSF priming shortened the time to achieve platelet engraftment compared with G-CSF alone. Prior exposure to melphalan delayed platelet engraftment and can lead to complete failure of platelet recovery. Stem cells should be collected before melphalan administration in patients with multiple myeloma who are candidates for possible blood cell transplantation.

Monoclonal plasma cells in the blood stem cell harvest from patients with multiple myeloma are associated with shortened relapse-free survival after transplantation.

We sought to determine whether circulating tumor cells in the blood stem cell harvest from patients with multiple myeloma are associated with a shortened disease-free survival. Prospective analysis was performed in 33 patients of blood obtained at leukapheresis for future transplantation. An immunofluorescence microscopy procedure identified the tumor cells by their morphology and monotypic light chain staining. Eighteen patients had increased (> or = 0.2 x 10(6)/l) monoclonal plasma cells circulating in the blood at stem cell harvest. Fifteen of the 18 have relapsed, with a median relapse-free survival of 6.2 months. Of 15 patients with < 0.2 x 10(6) cells/l, seven have relapsed, with a median relapse-free survival of 22.5 months (P = 0.008). Patients with circulating plasma cells showed a trend toward shorter overall survival (P = 0.078). In a multivariate analysis using the bone marrow plasma cell labeling index and beta 2-microglobulin, the absolute number of plasma cells in the stem cell harvest achieved borderline significance for predicting relapse-free survival (P = 0.057). In conclusion, increased monoclonal plasma cells in the blood stem cell harvest are associated with a shortened relapse-free survival. This does not necessarily indicate that the circulating plasma cells were responsible for relapse. These results, however, have implications with regard to the timing of obtaining blood stem cells for patients who are candidates for ablative chemotherapy.

Plateletapheresis with a next generation blood cell separator.

Procedure time has been identified as the-most important element in apheresis platelet donor retention. Fenwal has developed a next generation apheresis system, the Amicus, with the intent of efficiently producing high platelet yields with low WBC content in much shorter processing times than currently available. This report describes the Amicus and presents results of a clinical trial of an Amicus prototype and a comparison to Fenwal CS 3000+. Thirty Amicus double-needle plateletapheresis procedures were evaluated. Average processing time was 61 +/- 16 min with 63% of the processing times < or = 60 min. The average preplatelet count was 246 +/- 46 x 10(3)/microliter, platelet yield 4.4 +/- 1.2 x 10(11) plt, collection efficiency 73 +/- 14%, platelet collection rate 0.075 +/- 0.016 plt x 10(11)/min and citrate toxicity incidence 3%. A comparison of double-needle procedures, 20 Amicus and 20 CS 3000+, showed that Amicus had significantly shorter (P < .05) processing times (64 +/- 17 vs. 86 +/- 10 min) and higher (P < .05) platelet collection rates (0.070 +/- 0.017 vs. 0.054 +/- 0.018 plt x 10(11)/min) but comparable (P < .05) platelet yields (4.4 +/- 1.4 vs. 4.7 +/- 1.0 x 10(11) plt). Comparison of 13 single and 13 double-needle Amicus procedures showed comparable (P < .05) processing times (71 +/- 13 vs. 65 +/- 18 min), platelet yields (4.7 +/- 1.0 vs. 4.6 +/- 1.5 x 10(11) plt), collection efficiency (74 +/- 7 vs 74 +/- 17%), and platelet collection rates (0.068 +/- 0.020 vs 0.072 +/- 0.018 plt x 10(11)/min). Using normal probability plots of WBC content at 95% confidence level. Amicus can provide products with < 5.0 x 10(6)WBC or < 1.0 x 10(6) WBC in 99.7% or 92.7% of collections, respectively, compared with 69.0% or 44.0%, respectively, for CS 3000+. We found Amicus was able to provide equivalent quantities of platelets with less WBC content in significantly shorter processing times than CS3000+ as well as shown encouraging results for single-needle procedures.