Multicenter evaluation of methods for counting residual white cells in leukocyte-depleted red blood cells. The Biomedical Excellence for Safer Transfusion (BEST) Working Party of the International Society of Blood Transfusion

Two wet workshops were conducted involving 20 laboratories to determine optimum methods for counting residual white blood cells (WBC) in leukocyte-depleted red blood cells (RBC). In both studies, calibration samples containing known concentrations of WBC were prepared by diluting 1-day-old EDTA blood in RBC virtually free of WBC. Study No. 1 was aimed at determining the lower limit of detection and at examining advantages and disadvantages of two methods based on flow cytometry (FC) and on the Nageotte chamber (NC), respectively. This study showed that the lower detection limits for FC and NC were 0.1 and 1 WBC/microliters, respectively. Methods based on FC showed less variability at 0.1-1 WBC/microliters but were equal in performance to counting procedures based on the NC above 1 WBC/microliters. We then designed study No. 2 to evaluate three different protocols using the NC. In protocol 1, samples were diluted 1:10 with Plaxan and with Türk's solution; in protocol 2 a mixture of Türk's solution and Zap-oglobin, a reagent used in manual hemoglobin determinations, was used to dilute the samples 1:5; and protocol 3 involved initial 1:10 dilution of a 1-ml sample with Plaxan followed by WBC concentration into the original 1-ml volume by centrifugation. In each participating laboratory, two technologists independently processed the samples and read the results with an NC. Plaxan and Türk's solution gave comparable results. Interobserver variability was not critical to the results. All three NC methods were valid for counting at concentrations of > or = 1 WBC/microliters.(ABSTRACT TRUNCATED AT 250 WORDS)

Quality control of red cell filtration at the patient's bedside

BACKGROUND

Concern has been raised about the quality of white cell (WBC) reduction in blood components when it is performed by filtration at the patient's bedside. Thus, the quality of red cell (RBC) filtration performed at the bedside through two new flatbed WBC-reduction filters was evaluated.

STUDY DESIGN AND METHODS

In the laboratory, 25 and 10 RBC units suspended in additive solution were stored for 1 to 2 and 14 to 21 days, respectively, and filtered through each filter. At the end of filtration, an automated complete blood count and a manual WBC count (Nageotte chamber) were determined in two samples collected from 1) a segment clamped at 5 and 25 cm below the filter along the line connecting prefiltration and postfiltration bags and 2) the postfiltration bag. In addition, 10 of the 11 nurses of the hematology outpatient clinic administered to hematologic patients 25 RBC units stored for 1 to 2 days through each type of filter. At the end of transfusion, a segment was collected from the transfusion set and a WBC count was performed as described above. No filter priming or rinsing with saline was done.

RESULTS

WBC counts obtained after laboratory filtration in the segments were similar to those obtained from the postfiltration bags and from the segments collected at the bedside in all cases, with the exception of 14- to 21-day-old RBCs filtered in the laboratory through one of the filters, which produced slightly higher WBC counts in the segments than were seen in the postfiltration bags. The difference was not significant. In no case was the count in the postfiltration bag higher than that in the segment. Nurse training was easy, and bedside filtration was associated with no untoward effects.

CONCLUSION

The RBC filtration at the patient's bedside can be equal in quality to that performed in the laboratory, at least in such clinical settings as hematology and oncology departments in which blood transfusion is common practice, and if simple training is provided to the nursing staff. Under the conditions of this study, it seems that quality control of RBC bedside filtration is feasible and simple.

Single-donor platelet concentrates stored in synthetic medium. In vitro and in vivo studies

Single-donor platelet concentrates (PC) were prepared in 80-120 ml plasma and stored in two polyolefin bags after addition of 250 ml plasmalyte, a simple, glucose-free synthetic medium that was previously used for platelet storage; when compared to PC stored in plasma, PC stored in plasmalyte, showed similar platelet quality, morphology and function after 5 days of storage. In vivo increments observed after transfusion of PC stored for 5 days in plasmalyte were similar to those observed after transfusion of 1-2 day old PC stored in plasma. Moreover, transfusion of 5-day old PC stored in plasmalyte was associated with correction of prolonged bleeding times in all 3 of the 3 patients evaluated. It is concluded that plasmalyte seems to be promising as a medium for single-donor PC storage.

Role of lactate in platelet storage lesion

It is known that lactate accumulation may cause a pH fall in platelet concentrates (PC) during storage, and this phenomenon causes platelet morphological lesions and loss of platelet in vivo viability. In this study, we added increasing amounts of lactate to identical PC in order to evaluate the role of hydrogen ion accumulation in determining platelet activation and lesion during storage. Six hours after PC preparation, lactate was added to PC1 and PC2 at 20 and 12 mM final concentrations, respectively, while PC3 served as control. In PC1, pH was lower than 6.3, and platelet function and discoid morphology were lost. PC2 were stored for 7 days at pH values ranging from 6.4 to 6.6, and most results of in vitro measurements reflecting platelet function such as osmotic reversal, ATP release and aggregation in response to different stimuli were not significantly inferior when compared to controls. The addition of lactate had no apparent effect on the rise of platelet activation markers P-Selectin, lysosome-like protein gp 53, platelet-bound fibrinogen and granulophysin, while a reduction of borderline significance was observed in glycoprotein Ib expression after pH reduction to values lower than 6.6. It is concluded that the rise of platelet activation markers during storage reflects platelet lesions different from those determined by lactate per se.

A bioassay of thyrotrophin by photografted mammalian cells onto polymeric supports

Viable and functionally responsive human thyroid follicular cells, suspended in a commercial polyester acrylate diluted with tripropyleneglycol diacrylate, photoinitiated, and photocatalyzed with a proprietary photocatalytic system based on a synergic mixture of vanadium (V) t-butoxide and i-propoxide, have been immobilized as monolayers onto polystyrene plates. Bioassay of thyrotrophin in immobilized cell cultures yielded, by log-log plot of the dose-response curve, a slope (0.92 +/- 0.02) in close agreement with that (0.91) reported for cells immobilized by physical adsorption. The decisive role of photocatalyst in the photografting procedure has also been shown experimentally. A mechanism is suggested by which cells are anchored, rapidly and with stable chemical bonds, onto one of the two acrylate functions of the monomer-prepolymer mixture, the other one being simultaneously responsible for photochemical grafting onto the support.

White cell-reduced red cells prepared by filtration: a critical evaluation of current filters and methods for counting residual white cells

White cell (WBC) reduction, red cell (RBC) recovery, and filtration time were determined in 1-day-old standard and buffy coat-depleted RBCs filtered in the laboratory through six commercial filters for WBC reduction. Residual WBCs were counted with a Bürker chamber (BC), with a Nageotte chamber (NC), and by flow cytometry (FC). Results show that BC counts were 0 in several cases in which WBCs were detected with NC and FC, which indicated that the traditional BC method is too insensitive in use with currently available filters. Calibration curves performed by FC and with NC with samples containing known concentrations of WBCs from 1000 to 1 per microL showed that both FC and NC detected, on average, 67 percent of WBCs present in the samples (efficiency). However, the efficiency of FC showed small variability (61-70%) at different WBC levels, whereas the variability with NC was large (39-91%). This greater variability prevented the correction of NC counts by using a single factor and indicated difficulty in NC standardization. Therefore, because our main aim was to compare different filters rather than to define absolute levels of WBC contamination, uncorrected FC and NC counts were chosen to be reported. True WBC counts per unit should not exceed values that can be obtained by dividing uncorrected counts by the lowest efficiencies (61% for FC and 39% for NC). Uncorrected NC and FC counts were below 2 x 10(6) per unit in all units processed through three of the filters and below 5 x 10(6) per unit in all units processed through the other three.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet concentrates from buffy coats: improved conditions for preparation and evaluation in routine clinical use

Since 1990, platelet concentrates prepared by soft centrifugation of buffy-coat pools diluted with a glucose-free, commercially available crystalloid solution (BC-PC) are the first choice product for all platelet recipients in our institution. Numerous in vitro and in vivo observations from our own and other laboratories indicate that BC-PC compare favorably to PC prepared from platelet-rich plasma (PRP). In the present in vitro study we evaluated traditional and bottom-and-top bags and modified centrifugation conditions with the aim of increasing in vitro platelet yield in BC-PC. This was 14-18% higher compared with our previous protocol when prolonged centrifugation and bottom-and-top bags were used. In addition, we evaluated post-transfusion platelet count increments in 42 unselected adult hematological patients routinely transfused with 703 1-5 day-old BC-PC pools. Transfusion data were managed with PLATELET, an MS-DOS compatible program which includes automated calculation of transfusion efficacy and periodic patient reports. Mean pre-, 1 h and 24 h post-transfusion platelet counts were 16, 38 and 28x10 9/L, respectively. Mean 1 h and 24 h post-transfusion platelet count increments, expressed as percentage of expected, were 40 and 24%, respectively. These data were similar to those obtained previously in 189 unselected hematological patients given 2432 PRP-PC transfusions (mean 1 h post-transfusion increment 46% of expected). The present in vitro study confirms that similar platelet yields can be obtained with the BC and PRP methods. In vivo findings show that also in routine conditions post-transfusion increments of PRP-PC and BC-PC are similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoglobulin classes and subclasses of platelet antibodies in a case of post-transfusion purpura

A multiparous white woman developed severe thrombocytopenia following transfusion of red blood cells. Six ineffective platelet transfusions (a total of 42 random donor concentrates) were given from day 0 to day +6, high-dose steroids from day +1, progressively tapered until day +30, and a total of 150 g of intravenous immunoglobulins from day +2 to day +6. As platelet count had not increased significantly by day +8, four plasma exchange procedures, each consisting of 2,000 ml of plasma exchanged with 5% albumin solution, were performed on days +8, +10, +14 and +18. Platelet count was 5, 50, 100 and 234 x 10(9)/l on days +8, +14, +26 and +32 (discharge), respectively. The patient's acute phase serum contained increased levels of platelet alloantibodies with anti-HPA-1a (PlA1, Zwa) specificity and a titer of 3,200. IgG1, IgG2 and IgG3 subclasses of platelet-reactive antibodies in the patient's serum were elevated, whereas IgG4, IgM and IgA were within the reference values. Levels of IgG1, IgG2 and IgG3 of antiplatelet antibodies showed a marked and parallel reduction during treatment, but were still above the reference values at the end of treatment and 1 year later, when the patient platelet count was normal. Although a failure of intravenous immunoglobulins cannot be proven in this case, plasma exchange seems to have contributed more than intravenous immunoglobulins to clinical remission.

Incidence of AIDS in HIV-1 infected thalassaemia patients. European and Mediterranean W.H.O. Working Group on Haemoglobinopathies and Cooleycare

To estimate the cumulative incidence of acquired immunodeficiency syndrome (AIDS) in thalassaemia major patients (TMP) human immunodeficiency virus (HIV-1) infected through transfusion, 79 seropositive TMP were studied. At inclusion, mean age was 12.4 +/- 6.6 years; 40 were men; 21 were splenectomized. Centers for Disease Control, 1986 (CDC) stages and prescription of zidovudine were noted at least once a year. Cumulative incidence of AIDS and standard error were calculated using non parametric life table method. Age, sex, acute infection and splenectomy associations with progression to AIDS were tested using Breslow statistic. The median follow-up period was 4 years 11 months. At the end of the study period, 43 TMP were in CDC stage II, 23 in CDC stage III and 13 in CDC stage IV, including seven AIDS cases, of whom three had died. Four subjects died of other causes. Only two patients were treated with AZT prior to the occurrence of AIDS. Rate of progression to AIDS was not associated with acute infection, splenectomy, age, or sex. A cumulative AIDS incidence rate of 1.4% (SE 1.3%) was observed at 3 years and of 9% (SE 4%) at 5 years.

HIV and HTLV infections in 1305 transfusion-dependent thalassemics in Italy

OBJECTIVE

To evaluate the prevalence of antibodies to HIV-1/2 and HTLV-I/II in 1305 transfusion-dependent beta-thalassemics treated in 36 centres in Italy.

DESIGN

Patient serum samples were collected during 1990 and tested in Milan.

METHODS

Sera were screened using an enzyme-linked immunosorbent assay (ELISA) containing viral lysate antigens from HIV-1 and HIV-2, and a particle agglutination assay for the detection of antibodies to HTLV-I and HTLV-II. Repeatedly reactive samples were examined by Western blot (WB) assays containing recombinant and viral lysate antigens. Differential diagnosis was finally made by ELISA based on synthetic peptides.

RESULTS

Samples from 36 of the 1305 patients (2.76%) contained anti-HIV-1 antibodies. In four patients seroconversion occurred after the implementation of anti-HIV-1 screening in blood donors in Italy (1985). Of the 36 HIV-1-antibody-positive samples, four were HIV-2 [corrected] WB indeterminate. These four samples were negative in assays based on specific synthetic peptides, suggesting cross-reactivity. Anti-HTLV-I antibodies were found in two patients from Sicily and one from Apulia, both southern Italian regions. Anti-HTLV-II antibodies were detected in another patient from Sicily.

CONCLUSIONS

Antibodies to HIV-1, HIV-2, HTLV-I and HTLV-II were detected in 2.76, 0, 0.23 and 0.08% of patients, respectively. The residual risk of HIV-1 infection through blood transfusion after the implementation of anti-HIV-1 screening in blood donors in Italy was approximately 1:50,000 blood units; this is based on an approximate number of 200,000 blood units administered to our group of patients during 1986-1990 and the occurrence of four new anti-HIV-1 seroconversions. Seroconversions to HTLV-I/II suggest that these viruses are present in Italian blood donors.

Role of acetate during platelet storage in a synthetic medium

It has previously been shown that buffy coat platelet concentrates (BC-PCs) stored in a medium made up of approximately 70 percent platelet storage medium (Plasma-Lyte A, PL) and 30 percent plasma (BC-PC-P) are effective in vivo after 9 to 12 days of storage. In addition to sodium, potassium, magnesium, and chloride, PL contains 27 mM (27 mmol/L) sodium acetate and 23 mM (23 mmol/L) sodium gluconate. This study investigated the effect of acetate and gluconate on platelet metabolism. Identical BC-PCs were stored at 22 +/- 2 degrees C in PL (BC-PC-P); PL with gluconate but without acetate, termed PL-A (BC-PC-A); or PL with acetate but without gluconate, termed PL-G (BC-PC-G). On Day 1 of storage, no significant differences were seen between the three groups of BC-PCs. In both BC-PC-P and BC-PC-G, pH and bicarbonate were stable at 7.0 +/- 0.03 and 8.4 +/- 0.9 mEq per L throughout 10 days of storage, whereas in BC-PC-A, they fell to 6.7 +/- 0.05 and 5.5 +/- 0.8 mEq per L on Day 5 (p less than 0.01 vs. Day 1) and to 6.1 +/- 0.1 and 1.2 +/- 0.4 mEq per L, respectively, on Day 10. The buffering capacities of 70 percent PL, PL-A, or PL-G and 30 percent plasma were similar in a platelet-free setting when incremental additions of lactic acid were made. The role of acetate was further studied by adding 14C- or 3H-labeled acetate to BC-PC-P.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet quality after 15-day storage of platelet concentrates prepared from buffy coats and stored in a glucose-free crystalloid medium

It has been reported previously that platelet concentrates (PCs) prepared from buffy coat pools diluted in a simple, glucose-free medium (BC-PCs) are effective in thrombocytopenic patients after 4 to 12 days of storage. Such preparations produce platelet increments similar to those of traditional PCs prepared from platelet-rich plasma (PRP-PCs) stored for 1 to 3 days. The purpose of this study was to obtain a series of in vitro measurements during storage to allow a more detailed characterization of BC-PCs and a more detailed comparison of BC-PCs with PRP-PCs. At the beginning of storage, the level of (alpha granule membrane protein-140 (GMP-140), a marker of platelet activation, was significantly higher on PRP-PC platelets, and BC-PCs were superior in measurements reflecting platelet function, such as osmotic reversal, ATP release, and aggregation with collagen. Compared to PRP-PCs, BC-PCs were superior in the percentage of discs, total ATP, and glycoprotein lb expression by Day 7. This superiority became more striking on Day 11. Overall, 15-day-old BC-PCs compared favorably to 7-day old PRP-PCs: BC-PCs were superior in ATP release and aggregation with collagen, but they were not significantly different for all other measurements reflecting platelet quality and function. Thus, the quality of platelets in BC-PCs was superior on Day 1, and this superiority progressed as storage continued. In addition, the metabolism of BC-PCs was favorable.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of in vitro adherence of antibody-coated red cells to monocytes by the dialyzable leukocyte extract

The red cell-monocyte assay (RMA), which has been used to evaluate the clinical significance of red cell (RBC) antibodies, was employed to test the effect of the dialyzable leukocyte extract (DLE) on in vitro adherence to monocytes of human RBCs coated with alloantibodies or autoantibodies. The total association index (TAI) of the RMA, expressing the number of RBCs adhering to or phagocytosed by 100 monocytes, indicated a potent inhibitory activity of DLE in the test system. TAI values of 100.4 +/- 20.1 (mean +/- SD) in the control sample, consisting of RBCs coated in vitro with anti-D, dropped to 4.0 +/- 2.1 when DLE was present in the assay medium at a concentration of 0.5 U per mL. Similar results were obtained with RBCs coated with IgG antibodies in vivo. The inhibition was dose dependent and was associated with a thermolabile component of DLE. This study establishes that DLE can modulate monocyte function by inhibiting the recognition of IgG sensitized red cells.

Transfusion requirements and effects in patients with thalassaemia major. Cooleycare Programme

Analysis of data available in 1985 on 3468 Italian and Greek patients registered in Cooleycare, an international cooperative programme of quality assessment of treatment delivery in thalassaemia, gave the following picture of treatment requirements and effects. The proportion of patients undergoing splenectomy has progressively decreased, and age at splenectomy has increased with time over the past 20 years. Age at first transfusion exceeds 4 years in a small but important group of patients, which indicates that a milder form of thalassaemia exists in this group. Children receiving modern treatment remain of near-normal stature until age 11 but later tend to be stunted. The mean blood requirement is 35% higher in non-splenectomised than in splenectomised patients. Differences in transfusion interval of 2 to 4 weeks have no measurable effect on blood requirement. Mean blood requirement rises gradually with mean haemoglobin concentration, possibly in a non-linear fashion. The prevalence of red cell alloimmunisation rises with delay in start on transfusion. Transfusion reactions were reported in 1% of transfusions (90% of which were leucocyte-depleted), from 17% of patients.

Comparison of platelet activation and membrane glycoprotein Ib and IIb-IIIa expression after filtration through three different leukocyte removal filters

We evaluated three filters used for leukocyte removal from platelet concentrates: Imugard IG 500, Pall PL100 and Sepacell PL-10A. Filter performance, platelet activation and expression of membrane glycoproteins Ib and IIb-IIIa were evaluated. Imugard, Pall and Sepacell showed median postfiltration in vitro platelet recoveries of 88, 84 and 80%, and total residual leukocyte counts of 16.1, 7.5 and 0.6 x 10(6)/pool of 8 platelet concentrates, respectively. Mean platelet volume was reduced after filtration with all filters. Postfiltration values of glycoproteins Ib and IIb-IIIa, and of activation markers GMP 140 and gp 53 were not significantly different from prefiltration values. Filtration through Imugard, Pall and Sepacell did not induce significant platelet activation or modifications of platelet membrane glycoproteins Ib and IIb-IIIa.