Posttransfusion Platelet Count Increments Research Articles

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 28 × 10 9/L, respectively. Mean l 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. These observations further support previous studies indicating that, due to the better biochemical and metabolic conditions of BC-PC, the use of BC for platelet procurement is a good alternative to methods based on PRP. Large-scale cost analyses are warranted to validate this conclusion.

Detection and significance of alpha granule membrane protein 140 expression on platelets collected by apheresis.

Activation of platelets may be measured by using the monoclonal antibody S12 to detect alpha granule membrane protein 140 (GMP-140) antigen expressed only on activated platelets. S12 was used to measure activation of apheresis platelet concentrates by flow cytometry. Eleven platelet concentrates obtained by one method and nine obtained by another were analyzed 4 hours after collection. Means +/- 1SD of 25.3 +/- 14.8 percent and 28.9 +/- 11.6 percent, respectively, of platelets were found to be activated (range, 4.8-53.1%). Six of the platelet concentrates obtained by the second method were filtered. There was a drop of 17.8 percent (range, 10-25%) in the mean total number of platelets recovered after filtration, but there was no difference in the proportion of activated platelets measured immediately before and after filtration. The 1-hour posttransfusion platelet count increment was obtained after 12 of these apheresis platelet concentrates were transfused to eight patients who were not refractory from either a clinical or alloimmune standpoint. There was a significant inverse correlation between the platelet count increment and the proportion of activated platelets in the component (p less than 0.05, r = -.58). These data suggest that apheresis platelet concentrates with more activated platelets have a reduced 1-hour recovery. Filtration did not enhance activation or selectively remove activated platelets. Expression of GMP-140 may serve as a useful quality control measurement.

HLA antibody formation within the HLA-A1 crossreactive group in multitransfused platelet recipients.

The formation of intragroup antibodies, HLA antibodies directed against antigens in the same crossreactive group (CREG) as those of the serum donor, may be an important cause of transfusion failures in patients receiving HLA-matched platelets. Twenty-two patients whose HLA types included at least one antigen in the HLA-A1 CREG were studied. Of the ten patients who formed HLA antibodies, six produced antibodies that reacted with one or more antigens in the HLA-A1 CREG. Five of 12 patients whose HLA types included HLA-A3 formed antibodies directed against HLA-A1-10-11 or HLA-A1-10. In contrast, only one of ten individuals whose phenotypes included HLA-A1, HLA-A11, or both produced anti-HLA-A3. Eleven incompatible retrospective crossmatches were observed in recipients of HLA-matched platelets attributable to intragroup antibodies. Patients receiving incompatible platelets had unsatisfactory post-transfusion platelet count increments. It is concluded that intragroup antibodies, such as those directed against antigens in the HLA-A1 CREG, are an important cause of platelet transfusion failures in patients requiring long-term platelet transfusion support. These antibodies can be identified by routinely screening recipient sera for HLA antibodies and performing retrospective crossmatches using the lymphocytotoxicity technique.

抗ＨＬＡ抗体陽性の血小板輸血無効例に対する免疫グロブリン大量療法

High-dose intravenous immunoglobulin was given to eight patients who were refractory to platelet transfusions from random donors because of anti-HLA antibodies. They received intravenous infusions of polyvalent immunoglobulin (0.4g/kg/day for 5 days) just before random platelet transfusions. Two patients had an improvement in 20 hours post-transfusion platelet count increments and one patient had an improvement only in one hour post-transfusion platelet count increments. Five patients, however, had no improvement in one hour post-transfusion platelet count increments. After this therapy, titers of HLA-antibodies increased in three, unchanged in three and diminished in one patient. There was no relationship between post-transfusion platelet count increments and changes of titers of HLA antibodies.Random donor platelet concentrates or LCT-positive single donor platelet concentrates were incubated in vitro with polyvalent immunoglobulin at a final concentration of 3g/dl for 60 minutes at room temperature. Then those platelets were transfused to 4 patients. Following transfusion, one patient who had failed to respond to intravenous immunoglobulin therapy described above, had an increment at 20 hours. Three patients had no increment at one hour following transfusion.Nevertheless, on account of its cost, the exact place of this procedure in the management of such patients should be further documented with a prospecitve study.

Efficacy of platelet transfusions in immune thrombocytopenia

Records of 11 patients with immune thrombocytopenia (idiopathic and quinidine-induced) were evaluated retrospectively for response to platelet transfusion. Good post-transfusion platelet count increments occurred on one or more occasions in seven of the 11 patients, with 13 of 31 platelet transfusions (42 percent) resulting in immediate post-transfusion increments of 20,000/mm 3 or more. Next-day platelet counts remained elevated in association with five of these 13 transfusions. This study demonstrates that, contrary to common opinion, platelet transfusions can raise the platelet count in many patients with immune thrombocytopenia, and therefore may be beneficial in actively bleeding or high-risk patients with this disorder.

High-dose intravenous gammaglobulin in alloimmunized platelet transfusion recipients

High-dose intravenous gammaglobulin (polyvalent immunoglobulin G) has been shown to be of benefit in some patients with immune thrombocytopenic purpura (ITP), possibly by producing reticuloendothelial system blockade. We studied this approach in patients refractory to random donor platelet transfusion using an IV IgG preparation manufactured by the Swiss Red Cross. Eleven adult patients with acute leukemia received either 0.4 g IgG/kg/d intravenously X five days (four patients) or 0.6 g/kg/d X five days (seven patients). All patients had high levels of lymphocytotoxic antibody and poor responses to random donor platelets. Except for mild headaches in two patients, there were no side effects related to the IgG infusions. All patients had significant elevations of serum IgG on the day after completion of treatment. Either random donor or partially HLA-matched platelet transfusions were administered the day after and, in some cases, during the IgG therapy. No patient had an improvement in one hour posttransfusion platelet count increments. Two additional patients received pooled platelet concentrates incubated for 30 minutes at 37 degrees C with IgG at a final concentration of 3 g% prior to transfusions. These results indicate that high-dose IgG, an extremely expensive treatment, cannot be recommended for alloimmunized adults with leukemia.

High-Dose Intravenous Gammaglobulin in Alloimmunized Platelet Transfusion Recipients

High-dose intravenous gammaglobulin (polyvalent immunoglobulin G) has been shown to be of benefit in some patients with immune thrombocytopenic purpura (ITP), possibly by producing reticuloendothelial system blockade. We studied this approach in patients refractory to random donor platelet transfusion using an IV IgG preparation manufactured by the Swiss Red Cross. Eleven adult patients with acute leukemia received either 0.4 g IgG/kg/d intravenously X five days (four patients) or 0.6 g/kg/d X five days (seven patients). All patients had high levels of lymphocytotoxic antibody and poor responses to random donor platelets. Except for mild headaches in two patients, there were no side effects related to the IgG infusions. All patients had significant elevations of serum IgG on the day after completion of treatment. Either random donor or partially HLA-matched platelet transfusions were administered the day after and, in some cases, during the IgG therapy. No patient had an improvement in one hour posttransfusion platelet count increments. Two additional patients received pooled platelet concentrates incubated for 30 minutes at 37 degrees C with IgG at a final concentration of 3 g% prior to transfusions. These results indicate that high-dose IgG, an extremely expensive treatment, cannot be recommended for alloimmunized adults with leukemia.