Efficacy of HLA-matched platelet transfusions for patients with hypoproliferative thrombocytopenia: a systematic review

BACKGROUND

HLA-matched platelets (PLTs) are widely used to transfuse patients but the effectiveness of HLA matching has not been well defined and the cost is approximately five times the cost of preparing the random-donor PLTs. The objective of this systematic review was to determine whether HLA-matched PLTs lead to a reduction in mortality; reduction in frequency or severity of hemorrhage; reduction in HLA alloimmunization, refractoriness, or PLT utilization; or improvement in PLT count increment in patients with hypoproliferative thrombocytopenia.

STUDY DESIGN AND METHODS

We conducted a literature search of MEDLINE, Cochrane Controlled Register of Clinical Trials, EMBASE, and PubMed databases to April 2012.

RESULTS

A total of 788 citations were reviewed and 30 reports were included in the analysis. Most studies did not include technologies currently in use for HLA typing or detection of HLA antibodies as 75% were conducted before the year 2000. None of the studies were adequately powered to detect an effect on mortality or hemorrhage. HLA-matched PLTs did not reduce alloimmunization and refractoriness rates beyond that offered by leukoreduction, and utilization was not consistently improved. HLA-matched PLTs led to better 1-hour posttransfusion count increments and percentage of PLT recovery in refractory patients; however, the effect at 24 hours was inconsistent.

CONCLUSION

The correlation of the PLT increment with other clinical outcomes and the effect of leukoreduction on HLA-matched PLT transfusion could not be determined. Prospective studies utilizing current technology and examining clinical outcomes are necessary to demonstrate the effectiveness of HLA-matched PLT transfusion.

Platelet kinetics after slow versus standard transfusions: a pilot study

BACKGROUND

Platelet transfusion is required in the acute phase of some thrombocytopenic disorders in order to prevent potentially dangerous hemorrhages.The purpose of this study was to assess the increase in platelet count following a slow platelet transfusion.

METHODS

Patients suffering from thrombocytopenia due to various underlying diseases were enrolled in the prospective pilot feasibility trial and were randomly divided into two groups. Standard platelet transfusion was administered in one group, while slow transfusion was used in the other. The platelet count was examined at 1 hour, 24 hours, and 1 week following the transfusions.

RESULTS

Although the platelet count was higher following 1 hour after transfusion via the standard method, the count tended to be higher 1 week after the transfusion in the slow transfusion group. This difference, however, only turned out to be statistically significant amongst females.

CONCLUSION

A therapy of slow platelet transfusion might be more effective for the prevention of platelet loss. Further studies will be required to strengthen this hypothesis.

Autologous platelet transfusion in alloimmunized patients with acute leukemia

Seventy-eight transfusions of autologous platelets were given to eight alloimmunized patients receiving curative chemotherapy for acute leukemia. Platelets were collected at regeneration of hematopoiesis after a chemotherapy cycle, cryopreserved with 5% dimethylsulfoxide in liquid nitrogen, and retransfused during bone marrow aplasia following the next treatment cycle. The in vitro platelet recovery after freezing, thawing, and washing was 85 +/- 4%. The in vivo corrected count increment 1 h after autologous platelet transfusions was 11 +/- 5 x 10(9)/l. With the exception of moderate urticaria and slight nausea each after one transfusion, no immediate or chronic side effects occurred. The bleeding time was shortened and hemorrhage during bone marrow aplasia was prevented in all alloimmunized patients by autologous platelet transfusions.

Relative importance of immune and non-immune causes of platelet refractoriness

In this prospective study, 26 consecutive patients being treated for haematological malignancies receiving standard (i.e. non-leucocyte-depleted) blood components were observed for the development of refractoriness to platelet transfusions. One hundred and sixteen of the 266 (44%) platelet transfusions failed to produce a satisfactory response. In 102/116 (88%), the poor response was in the presence of non-immune factors known to be associated with platelet refractoriness. Non-immune factors were present alone in 78/116 (67%), and in combination with immune factors in a further 24/116 (21%). Immune factors (HLA and platelet-specific antibodies) were present during 29/116 (25%) of unsuccessful platelet transfusions. Statistical analysis confirmed that platelet refractoriness was significantly associated with the presence of non-immune factors. The non-immune factors associated with refractoriness were often multiple, most frequently a combination of fever, infection and antibiotic therapy. This study provides evidence that immune mechanisms were not the predominant cause of platelet refractoriness in the patient population studied. It also suggests that measures for the prevention of HLA alloimmunisation, such as leucocyte depletion, may have a limited impact in reducing the incidence of refractoriness to platelet transfusions.

The role of ABO matching in platelet transfusion

A prospective controlled trial was performed to determine whether the use of ABO-identical platelets from the start of treatment might provide higher post-transfusion platelet increments, reduce the number of platelet transfusions and ultimately delay the onset of refractoriness. Forty newly diagnosed patients with haematological diseases were randomized to receive either pooled ABO-identical platelets or pooled platelets unmatched for ABO group throughout their course. The corrected platelet count increments (CCI) were calculated for the first 25 transfusions of each patient and non-immune factors present at the time of each platelet transfusion were documented. The mean CCI for the first 25 transfusions in the ABO-identical group was significantly higher (6600 +/- 7900 SD) than that achieved with ABO unmatched platelets (5200 +/- 7900; p < 0.01). The effect was most marked for the first 10 transfusions for each patient where the CCI was 64% higher in the ABO-identical group (8200 +/- 7500 vs 5000 +/- 8100; p < 0.0002). Patients given ABO-identical platelets required only about half as many transfusions in the first 30 days (10 versus 17, p < 0.05) or during the first admission (11 versus 21 p < 0.01) as patients in the ABO-unmatched group. A smaller percentage of patients in the ABO-identical group became refractory (36% vs 75% p < 0.03). The data suggest that patients requiring long-term platelet support should be transfused with ABO-identical platelets.

Elevation of platelet-associated IgG in aplastic anemia

We determined platelet-associated IgG (PAIgG) levels in patients with aplastic anemia, idiopathic thrombocytopenic purpura (ITP), iron deficiency anemia, and systemic lupus erythematosus (SLE), as well as in normal healthy adults as a control group. To determine PAIgG levels, we used a competitive micro enzyme-linked immunosorbent assay, which had excellent reproducibility, recovery, and dilution. We confirmed its reliability by comparing it to the immunoradiometric assay. Both the aplastic anemia group (n = 27, mean +/- SD = 218.6 +/- 244.6 ng/10(7) platelets) and the ITP group (n = 82, mean +/- SD = 212.5 +/- 327.8 ng/10(7) platelets) had higher PAIgG levels than the SLE group (n = 4, mean +/- SD = 38.4 +/- 22.4 ng/10(7) platelets), iron deficiency anemia group (n = 10, mean +/- SD = 16.1 +/- 3.6 ng/10(7) platelets), and normal control group (n = 69, mean +/- SD = 16.1 +/- 3.6 ng/10(7) platelets. The higher platelet-associated IgG levels in aplastic anemia suggest that autoimmune mechanisms are involved.

A prospective randomized trial of HLA-matched versus mismatched single-donor platelet transfusions in cancer patients

The use of histocompatability antigen (HLA)-matched platelets has been advocated for the support of thrombocytopenic cancer patients. We randomized 78 newly diagnosed cancer patients prospectively (before thrombocytopenia) to receive either HLA-matched or mismatched single-donor platelet transfusions. Three hundred forty-one platelet transfusions were given for 80 separate episodes of therapy-induced thrombocytopenia in 33 patients. Forty-five patients receiving intensive chemotherapy did not develop significant (less than 20,000 platelets/mm3) thrombocytopenia and did not receive a platelet transfusion. No marked difference was observed between the matched and mismatched groups in regard to number of total platelet transfusions per patient (median, 3 vs. 5, respectively; P = 0.076), number of platelet transfusions per episode (median, 3.0 vs. 3.5, respectively; P = 0.28), or days between transfusions (median, 2 vs. 2, respectively, P greater than 0.4). Bleeding episodes, although rare, tended to be of increased severity in the mismatched group. Febrile patients receiving mismatched platelets tended to have a lower posttransfusion increment increase than their nonfebrile counterparts (P = 0.068), although a similar trend could not be demonstrated between febrile and nonfebrile patients who received matched platelets (P = 0.22). Patients treated as outpatients had significantly higher posttransfusion increments than when transfused as inpatients when they were given mismatched platelets (P less than 0.0005). Development of antiplatelet antibody did not appear to affect response to platelet transfusions. Only one patient developed sustained high-level antibody titers. In patients where thrombocytopenia was significant, the transfusion of HLA-matched platelets did not appear to offer a significant advantage. However, HLA-matched platelet transfusions tended to be associated with higher posttransfusion increments in febrile patients and a trend toward fewer severe bleeding episodes. A multi-institution trial containing a large number of patients is needed to evaluate trends observed in this study.

Bone marrow transplantation in patients with leukaemia previously transfused with blood products from family members

Transfusions are withheld, whenever possible, from patients with aplastic anaemia who are potential bone marrow transplant recipients because of the increased risk of graft failure associated with transfusions prior to transplantation. Family members are specifically excluded as blood product donors to reduce the likelihood of sensitizing the recipient to antigens shared by the blood and bone marrow donor. This policy of not using family members, particularly the HLA-matched bone marrow donor, to provide blood products prior to transplantation has been extended to leukaemia as well. To evaluate this policy we reviewed the outcome of bone marrow transplantation in 18 patients with leukaemia transfused prior to transplantation with platelets and/or leucocytes from related family members. In 15 cases in which the outcome could be evaluated, engraftment was rapid and graft failure did not occur. Transfusion of blood products from related family members to patients with leukaemia prior to transplantation does not appear, therefore, to increase the risk of graft rejection.

Canine platelet alloimmunization: the role of donor selection

Five different platelet transfusion programmes were evaluated in a canine model to determine the most effective method of providing long-term platelet support. When a weekly transfusion from a single unrelated donor was used, alloimmune platelet refractoriness developed in 95% of recipients after an average of 3.1 +/- 0.7 transfusions, and donor platelets circulated for a total of 8.2 +/- 2.3 d. When multiple unrelated donors were used, the percentage of refractory recipients was similar (60% versus 77%) whether platelets came from six single donors given sequentially or from a pool of the same six donors given repeatedly. There was, however, a significant difference in the number of transfusions given prior to immunization (14 +/- 5 transfusions lasting 32 +/- 12 d for sequential single donors as compared to 5.5 +/- 1.0 transfusions lasting 13 +/- 2 d for the pooled donors). When littermates were used as platelet donors, the frequency of refractory recipients, the number of transfusions required to immunize, and the circulation time of donor platelets before refractoriness was not better than when multiple unrelated single donors were used. Furthermore, there was no significant difference in effectiveness between DLA-identical and DLA-nonidentical littermate platelet donors. In recipients previously immunized by a pool of six unrelated donors, the same percentage of recipients was refractory to DLA-identical littermate donors as had been observed following only DLA-identical platelet transfusions. This suggests that non-DLA immunizing platelet antigens, not shared between approximately 30% of DLA-identical littermates, are well represented in a random canine population. However, prior random transfusions did not compromise long-term platelet support from 'truly' platelet compatible DLA-identical littermate donors. These studies indicate that single donor transfusions either from littermates or sequential unrelated donors are the most effective method of providing long-term platelet support. However, the use of pooled unrelated donor transfusions, followed by DLA-identical donors in immunized recipients is an equally acceptable alternative.

Use of leucocyte-poor blood components and HLA-matched-platelet donors to prevent HLA alloimmunization

Recent studies have shown that the incidence of alloimmunization due to repeated platelet transfusions from random donors may be reduced by the use of leucocyte-poor blood components. These results were confirmed by this study, where 16% of patients with acute leukaemia undergoing initial chemotherapy and receiving leucocyte-poor blood components developed lymphocytotoxic antibodies, compared with 48% of patients in a control group receiving standard (non-leucocyte-depleted) blood components. In a third group, who received leucocyte-poor blood components and HLA-matched platelets, none of the patients developed lymphocytotoxic antibodies. There was a low incidence of platelet-specific antibodies (8%) but no difference between the three groups. Improved methods of removing leucocytes from blood components appear to offer the best approach for minimizing HLA alloimmunization, as the provision of HLA-matched platelet donors for prophylactic platelet support of all patients is not feasible.

High dose intravenous gammaglobulin and platelet transfusions in leukaemic HLA-immunized patients

3 aplastic patients with acute leukaemia, strongly HLA-immunized and refractory to platelet transfusions, received polyvalent gammaglobulin i.v. infusions (0.4 g/kg/d for 5 or 6 d) in association with daily random platelet transfusions. Platelet recovery was obtained in 2 patients. The 3rd patient did not show any significant rise in platelet count. The ability of gammaglobulin to prolong the life-span of incompatible transfused platelets could facilitate the management of HLA-immunized patients.

Autologous cryopreserved platelets and prophylaxis of bleeding in autologous bone marrow transplantation

Autologous platelets were harvested and cryopreserved in eight consecutive patients elected for ablative chemotherapy and autologous bone marrow transplantation (ABMT) for solid malignancy. There was a 19% loss in platelet count after the freeze thaw and wash procedure; with an in vitro functional loss of 40-60%. No correlation could be found for individual platelet transfusions between in vitro functional tests and in vivo recovery. Six consecutive patients received a total of 16 autologous platelet transfusions in the aplastic phase of ABMT. No bleeding was observed during the study period and there was no CMV infection in the recipients. While improvement in freezing and subsequent handling is desirable, autologous cryopreserved platelets can safely be used for the prophylaxis of bleeding during aplasia in patients treated with ABMT.

Rh-incompatible platelet transfusion therapy in cancer patients. A study of 30 cases

The clinical histories of 30 consecutive Rh0D-negative oncology patients transfused with Rh0D-incompatible platelet concentrates were analyzed. No evidence of sensitization to the Rh0D antigen was found whatsoever, in spite of the large numbers of Rh0D-incompatible platelet transfusions given to these patients. The results of this work seem to indicate that patients with malignant diseases, who are undergoing various forms of antineoplastic therapy, are immunomyelosuppressed, and have severe thrombocytopenia, can safely receive platelets from Rh0D-positive donors without developing evidence of immunization to Rh0D antigens.

Preparation of leukocyte-free platelets for transfusion by filtration through cotton wool

Filtration through Imugard filters of random platelet concentrates or platelets obtained by plateletpheresis allow the preparation of leukocyte-free platelets for transfusion. The procedure is simple and determines only a small platelet loss (less than 10%). Filtered platelets seem to function normally in vivo. The use of leukocyte-free red cell and platelet transfusions for the support of patients suffering from leukemia or aplastic anemia could prevent major complications, such as refractoriness to platelet transfusion and to bone marrow transplantation.

Serological studies in patients on platelet- and granulocyte-substitution therapy

A serological follow-up study was undertaken in 47 patients with bone-marrow failure, who were repeatedly transfused with random donor granulocytes and/or platelets. Sera, obtained at regular intervals, were investigated in the leucoagglutination test, the lymphocytotoxic test and the immunofluorescence test on paraformaldehyde-fixed platelets, granulocytes and lymphocytes. The frequency of alloimmunization was high (73%). Not only HLA antibodies, but also blood-cell-specific alloantibodies were detected in the sera of the alloimmunized patients, e.g. lymphocyte-specific, platelet-specific and granulocyte-specific antibodies. The immunofluorescence test on platelets was also used as a crossmatch, and when this test was positive it was always found that after platelet transfusion the increment value was nil.

A cross-matching procedure for the selection of platelet donors for alloimmunized patients

A platelet cross-matching procedure has been assessed for selecting compatible donors for alloimmunized patients. This confirms the clinical value of combining an indirect platelet immunofluorescence test (PIFT) with a lymphocytotoxicity test (LCT) in predicting the survival of single-donor platelets. There was good agreement between the PIFT cross-match and post-transfusion platelet recovery. Compatibility in the LCT alone was insufficient for platelet donor selection, as this test did not detect all antibodies affecting platelet survival. Positive LCT and PIFT cross-matches indicated the presence of HLA antibodies. Inclusion of an indirect lymphocyte immunofluorescence test (LIFT) helped to classify the platelet antibody when the LCT cross-match was negative. In such cases, parallel positive findings with the LIFT and PIFT suggested a cytotoxic-negative antibody of probable HLA specificity active against platelets. Disparity between the LIFT and PIFT was also observed; a strongly positive PIFT along with a weak reaction in the LIFT suggested that a platelet-specific antibody was responsible for the poor platelet survival in these cases. This study has also shown the presence in multitransfused patients of LIFT-positive antibodies not reacting in the LCT and PIFT, which do not affect the survival of transfused platelets. A positive granulocyte cross-match was demonstrated in patients with febrile rigors associated with compatible platelet transfusions. Splenectomy and steroids may improve the survival of incompatible platelets depending on the nature of the platelet antibody.

In vitro tests for platelet compatibility

Four methods were investigated to determine their suitability as platelet compatibility procedures: leukoagglutination, lymphocytotoxicity, platelet suspension immunofluorescence and platelet enzyme-linked immunosorbant assay. None of the tests were found to reliably predict the 24-hour-posttransfusion platelet increment in 8 refractory thrombocytopenic patients judged refractory to random donor platelet therapy.

Recognition of a non-HLA-ABC antigen present on B and T lymphocytes and monocytes only detectable with the indirect immunofluorescence test

The serum of a 39-year-old male under long-term platelet transfusion therapy for hypoplastic anemia with thrombocytopenia was investigated for the presence of leukocyte and platelet antibodies after the patients had received platelet concentrates from more than 700 random donors. The serological studies of his serum revealed: (1) the absence of platelet-reactive antibodies; (2) the absence of agglutinating or cytotoxic antibodies against leukocytes; (3) the presence of at least two granulocyte-specific antibodies, one with the specificity anti-NA2 and the other with an undefined specificity, both only detectable by indirect immunofluorescence, and (4) the presence of cytotoxic-negative fluorescence-positive peripheral-blood-mononuclear-cell-reactive antibodies, not directed against HLA-A, B or C antigens. The significance and implications of these findings are briefly discussed.

Complement-dependence of platelet serotonin release test in polytransfused patients

The research of platelet isoantibodies in patients with Cooley's anaemia was performed by simultaneous determination of the platelet-complement fixation test, platelet factor 3 availability assay and 14C-serotonin release test. In 93% of the examined patients we obtained positive results with the 5HT-release test, which appeared to be a complement-dependent reaction in most of the sera-containing isoantibodies, different from sera of patients affected by autoimmune thrombocytopenia.

Platelet transfusion therapy

Platelet transfusions are of unquestionably proven benefit for the correction of thrombocytopenia or functional platelet disorders, and they have allowed for more intensive antineoplastic therapy. With the advent of blood component therapy most modern blood banks now have the capabilities for supplying at least limited quantities of platelets. Refinements in procurement methods will inevitably lead to a greater supply of platelets and the establishment of larger transfusion programs. These programs will need to incorporate facilities for platelet storage, recruitment of suitable donors, selection of special donors for refractory patients, and methods for quality control. As antineoplastic therapy becomes more aggressive, such transfusion programs will become an integral part of the operation of cancer treatment centers.

Statewide support of thrombocytopenic patients with ABO matched single donor platelets

Use of ABO matched, HLA nonmatched platelet units obtained from single donors by pheresis, using the Haemonetics 30 Cell Separator, has a lowered hepatitis risk, and possibly delays the onset of the refractory state. Pheresis also offers a method of obtaining HLA matched platelets for the already refractory patient. A mean of 4.2 X 10(11) platelets are collected in about 1 1/2 hours. ABO matched, HLA nonmatched platelets produced corrected increments of more than 2500/mm3 per 7 X 10(10) platelets infused in 67 per cent of transfusions to nonselected recipients. The procedure is simple, safe, and requires little time. It is a worthwhile large-scale program for a regional blood center to undertake in order to provide optimal therapy for thrombocytopenic patients.

Rhesus monkey platelet kinetics and storage

Rhesus monkey platelets that are separated, 51Cr labeled, and transfused provide yields, 1/2 time and survivals similar to those obtained in man. Rhesus platelets prepared and stored at room temperature for three days have 93 per cent of the yield of fresh platelets. When prepared and stored at 4C, the yield is only 54 per cent of fresh platelets. Rhesus repeatedly transfused with platelets from random unmatched donors always have a significant decrease in the platelet 1/2 time and survival. This was observed after the second homologous transfusion in one and after the third in others. The rhesus provides an excellent platelet model with thrombocyte responses mimicking those of man.

Cross-reactivity of monospecific anti-HL-A antisera

32 'monospecific' anti-HL-A alloantisera were absorbed in separate tests with platelets from a maximum of 56 different persons and examined for residual cytotoxicity against target lymphocytes from one or two unrelated persons having the homologous (or test) antigen. Of the 799 combinations in which platelts had the test antigen, 715 (90%) were specifically inhibited; of the 720 combinations in which platelets had the cross-reactive antigen(s) (but not the test antigen), 417 (58%) were specifically cross-inhibited; and of the 1,839 combinations in which platelets had neither the homologous nor a discernable cross-reactive antigen, 133 (7%) were cross-inhibited 'nonspecifically'. Earlier findings of cross-reactivity were confirmed, and results suggested that HL-A1, HL-A10 and W30 on platelets may cross-inhibit anti-HL-A2 antibodies; HL-A7 and W21 may cross-inhibit anti-HL-A5 and anti-W5 antibodies; W16 may cross-inhibit anti-HL-A5 antibodies; and W22 may cross-inhibit anti-HL-A13 antibodies.

Functional and ultrastructural status of platelets prepared by the Celltrifuge

Function and morphology of platelets collected by the Celltrifuge were investigated. In vitro platelet tests included aggregation by adenosine diplhosphate, collagen, and epinephrine, ability to support clot retraction, uptake and release of labeles serotonin, and morphology at the ultrastructural level. Each of these tests was also performed on platelets obtained from the same donor before the collection procedure was instituted. Data obtained from pre- and post-Celltrifuge platelet samples were compared and analyzed on individual donor basis as wass as on eight donors as a group. The hemostatic effectiveness of Celltrifuge-collected platelets was evaluated by their ability to raise platelet counts and to shorten the template bleeding time in four thrombocytopenic recipients. Our results indicate that platelets prepared by this continuous flow centrifugation equipment retained their functional and ultrastructural integrity, and significantly raised the platelet counts and shortened the bleeding time of all four patients.

Effect on platelet counts and fever of platelet transfusion in leukemia

The efficacy of platelet transfusions in pretransfused HL-1 sensitized patients has been doubtful, particularly where repeated platelet transfusions were required. The efficacy of one hundred and nine ABO-compatible, cross match negative platelet transfusions in 26 adult patients with acute leukemia was therefore studied. Although most of the patientswere old and pretransfused and although no HL-A typing could be made, a statistically significant average increase of about 11 000 platelets/mul was seen not only after the first but also after subsequent (up to 8) platelet transfusions. Moreover, significant reduction in temperature followed platelet transfusions. However, platelet recoveries were worse in severely infected patients.

[Supportive care in bone marrow failure. Technical, immunological and clinical advances]

Supportive care with blood component transfusions has greatly improved prognosis in patients with bone marrow failure. This progress has made possible by newly developed techniques for separation of blood cells and by a better understanding of the antigenicity of human blood cells and of immunologic reactions following their transfusion. Transfusion of white cell and platelet-poor red cell preparations prevent alloimmunization to leukocyte and platelet-bound alloantigens, or non-hemolytic transfusion reactions in already alloimmunized patients. Alloimmunization can be circumvened and effective long-term platelet support to thrombocytopenic patients can be provided by matching donor and recipient for HL-A antigens. The place of granulocyte transfusion in clinical therapy has yet to be defined, although their usefulness in infected granulocytopenic patients is suggested by the few studies reported so far.