Dashed lines symbolize 95% confidence intervals. == Required pool sizes to complement 80% from the patient populace with at least five donors == Pools of 31, 940, 1710 and 321 donors would be necessary to provide at least five CC, PC or LC donors to 80% from the patients, respectively according to the projection model (Figure 1, Physique 2, Physique 3). grading system of Duquesnoy. == Results == Using the mathematical model, a pool containing 31, 940, 1710 and 321 donors would be necessary to match more than 80% of the patients with at least five completely compatible (no cross-reactive group), partial compatible (one cross-reactive group) or much less compatible (two cross-reactive group) donors, respectively. == Bottom line == The phenotypic diversity of the Brazilian population offers probably made it more difficulty to find completely compatible donors. However , this heterogeneity seems to have facilitated obtaining donors when cross-reactive groups are accepted as proposed by the grading system of Duquesnoy. The results of this study may help to establish unrelated human being leukocyte antigen-compatible platelet transfusions, a procedure not routinely performed in most Brazilian transfusion solutions. Keywords: Platelet transfusion, HLA, Refractoriness, Donors == Intro == Platelet alloimmunization is commonly seen in patients with hemato-oncological disorders requiring frequent red blood cell and platelet transfusions1and may be associated with refractoriness to platelet transfusions (RPT). There may also be an association between platelet transfusion failure and patient survival, which increases the clinical importance of RPT. 2 RPT is defined as inappropriately low platelet count number increments following exposure to antigens after two or more (usually consecutive) transfusions and must be determined by objective data which determine platelet transfusion outcomes. 3This condition may be caused by immune and non-immune factors. More than 80% of RPT cases are related to non-immune causes. Thus, immune causes occur in less than 20% of the cases involving alloimmunization against human being leukocyte antigens (HLA) and, to a lesser extent human being platelet antigens (HPA), following exposure after transfusion, pregnancy, or transplantation. Among the immune causes, HLA antibodies are responsible for approximately 8090% of RPT cases and HPA antibodies for approximately 1020% of cases, associated or not with HLA antibodies. 4 Providing an adequate post-transfusion platelet count increment to refractory patients is not an easy task; transfusion of HLA-matched platelets is one possibility. 5However, it is very difficult to find multiple HLA-compatible related donors for one individual. The HLA system is highly polymorphic6and the probability of finding identical matches may be around 10% of donations. 7, 8When a full match cannot be discovered, different strategies are used to select partially HLA-matched donors. HLA class I specificities can be grouped into cross-reactive groups (CREG), Fasudil HCl (HA-1077) mismatches with antigenic similarity that result in much less allorecognition or immune activation. 9The grading system explained by Duquesnoy et al. in the 1970s10(Table 1) is defined according to Fasudil HCl (HA-1077) the presence of HLA CREGs and is still widely used by transfusion solutions. Although in some cases, the selection of mismatched donors based on HLA CREGs may fail to produce adequate increments, 11this strategy can increase the number of potential donors in the same donor base. 8 == Table 1 . == Description of the grading system of Duquesnoy. R: recipient; D: donor; HLA: human being leukocyte antigen;: undetected antigens. Pool size calculations can be an essential component for the rational planning of platelet support programs. 12It is estimated that to provide at least five completely compatible donors for more than 80% of patients, 500, 1000, and 1500 donors would be needed for the Japanese, European Caucasoid and North American Caucasoid populations, respectively. 13However, for a highly mixed population such as in Brazil, which is comprised of European, African and Amerindian roots, 14the pool size required to provide these patients with adequate platelet support is unknown. The unrelated donor pool size that might be necessary if a center wants to provide patients with unrelated HLA-compatible platelets was estimated using a arbitrary sample from the Brazilian populace. A mathematical model was created for compatibility analysis as well as application was illustrated Rabbit Polyclonal to IKK-gamma (phospho-Ser31) in a population of 154 cancer patients. The findings of this study may help to establish the transfusion of unrelated HLA-compatible platelets, which currently is not a routine procedure in many Brazilian centers. == Methods == == Study database, design and setting == A group of 154 HLA-typed patients who were submitted to bone marrow transplantation or who were candidates for this procedure at Hospital Israelita Albert Einstein (So Paulo, Brazil) between January 2006 and December 2009 were included in this retrospective study to illustrate a possible patient populace. A database of 65, 500 HLA-typed bone marrow donors, registered in the LIG Laboratrio de Imunogentica Ltda, So Paulo, Brazil was used in this study as the potential donor populace. This database includes samples from the southeastern (mainly), southern and northeastern regions of Brazil and represents a section of the National Registry of Fasudil HCl (HA-1077) Bone Marrow Donors. In accordance to a Brazilian demographic census, these regions are related to 80% from the population15and may represent a great picture.