Intravenous immune globulin use in patients with human immunodeficiency virus-related thrombocytopenia who require dental extraction.

Five patients with human immunodeficiency virus (HIV)-related immune thrombocytopenia who were undergoing dental extraction were treated with intravenous immune globulin (IVIG). All patients received IVIG, 1 gram per kg, the day before the dental extraction and again the day of the dental extraction. Four patients had a previous history of minor clinical bleeding. The median baseline platelet count before extraction was 20 X 10(9) per liter (range 13 to 44). The median peak platelet count was 100 X 10(9) per liter (range 56 to 528) following infusion. This peak response was achieved by day 2 in 3 patients and by days 5 and 7 in 1 patient each. No patients had complications or toxicity from the infusions or perioperative bleeding. No patients required blood product transfusions for the surgical procedure. In conclusion, IVIG infusion should be considered in patients with HIV-related immune thrombocytopenia requiring surgical procedures when a prompt rise in platelet count is desired.     

Use of platelet concentrate in eastern Ontario.

To better understand the reasons for the increasing use of platelet concentrate in Canada, we undertook a 4-month study of platelet concentrate transfusion in six eastern Ontario hospitals in 1985. A total of 4801 units of platelet concentrate were transfused on 687 occasions to 303 patients; the average number of transfusions per patient was 2.3, the average number of units per transfusion 7.0 and the average number of units per patient 15.8. The cardiovascular service used the largest proportion of units (28%), aortocoronary bypass grafting being the most common procedure. The mean pretransfusion platelet count for the medical and oncology services was about 30.0 X 10(9)/L, compared with 155.5 X 10(9)/L for the cardiovascular service. An increment in platelet count 1 hour after transfusion was noted with 238 (75%) of the transfusions for which the data were available; the average increment was 3.4 X 10(9)/L per unit of platelet concentrate transfused. When the data for patients who did not respond were excluded, the average increment was 6.9 X 10(9)/L. Single-donor platelet concentrate was requested for only half of the transfusions to which no response was detected. The current medical literature supports the appropriate use of platelet concentrate in patients with thrombocytopenia due to chemotherapy, but prophylactic platelet transfusion for patients undergoing cardiovascular bypass procedures is being questioned. We advise continued surveillance of the use of these products and re-evaluation of the aims of platelet transfusion therapy.     

ITP in pregnancy: use of the bleeding time as an indicator for treatment

ITP is a relatively common disorder seen in pregnancy. Current recommendations for management of patient with ITP recommend maintaining the platelet count above 50 x 10(9)/L and the bleeding time less than 20 min. It has been well documented that the bleeding time in ITP is disproportionately shortened in many patients relative to the platelet count. We present a prospective study of 24 ITP patients in whom the bleeding time was used as an indicator for therapeutic intervention in pregnancy. Indications for therapy with prednisone and/or intravenous gammaglobulin were the following: significant clinical hemorrhage due to thrombocytopenia; bleeding time of greater than 20 min at the baseline platelet count; for normalization of hemostasis prior to delivery or surgical procedure. Caesarean section was performed only in cases in which there were obstetrical indications for this mode of delivery or when the fetal platelet count (obtained by fetal scalp vein sample) was less than 50 x 10(9)/L. Of 24 patients with ITP, eight had significant thrombocytopenia (platelet count less than 50 x 10(9)/L) throughout pregnancy. Only two patients required prolonged prednisone therapy. Both suffered side effects of chronic prednisone administration. Four patients were treated with prednisone for a short course (10-14 days) at term to improve hemostasis for delivery. One patient was treated with intravenous gammaglobulin at term in an effort to prevent severe neonatal thrombocytopenia. Seven patients required caesarean section; the remaining 17 patients underwent vaginal delivery. Only one minor bleeding complication was seen - a small wound hematoma post caesarean section. In summary, using the bleeding time as an indicator for therapeutic intervention, treatment of ITP in pregnancy can be minimized. Thus, therapy related toxicity can be avoided.     

Treatment of autoimmune thrombocytopenic purpura with rhesus antibodies (anti-Rh0(D)]

There is evidence that blockade of the reticuloendothelial system (RES) by sequestration of autologous red blood cells (RBC) leads to an elevation of platelet counts in immune thrombocytopenia. To substantiate this hypothesis, 10 Rh0(D)-positive adult patients (9 female, 1 male) with chronic autoimmune thrombocytopenic purpura (ITP) (1 to 21 years duration) were treated with low doses of intravenous IgG-anti-Rh0(D) (200 to 1,000 micrograms per dose; 300 to 3,600 micrograms per course; administration within 1 to 5 days). All patients improved clinically as indicated by cessation of bleeding. In eight out of ten patients there was a rise in platelet count. Platelet increments were excellent (greater than 100 X 10(9)/l) in one, good (50-100 X 10(9)/l) in three, fair (20-50 X 10(9)/1) in two and low (10-20 X 10(9)/1) in two patients. Splenectomized patients (N = 4) had a poorer response than non-splenectomized patients (N = 6) with mean increments of 16 X 10(9)/l (range 5-43 X 10(9)/l) versus 60 X 10(9)/l (range 10-110 X 10(9)/l). The increase in platelet counts persisted for seven to over 150 days. Transient and slight signs of haemolysis developed in seven out of ten patients (haemoglobin remained stable; increase of lactate dehydrogenase (greater than 250 IU/l) in four, decrease of haptoglobin (less than 60 mg/dl) in five patients). The direct antiglobulin test became positive in all cases due to IgG1 without complement fixation. We conclude that the interaction of antibody-coated RBC with macrophages (and, probably, other means of RBC alteration) is a feasible therapeutic approach in selected cases of ITP and related conditions.     

The treatment of neonatal isoimmune thrombocytopenia with intravenous immunoglobin (IgG i.v.)

We present a report of the use of IgG i.v. to treat clinically manifest neonatal immune thrombocytopenia. The IgG i.v. was administered at a daily dosage of 0.4 g/kg body weight for 5 days. Treatment was started when the child was 3 days old and had a platelet count of 2 X 10(9)/l. Four days later the platelet count had risen to 200 X 10(9)/l. The diagnosis of immune thrombocytopenia was confirmed by platelet typing of the mother's and child's platelets and identification of anti-platelet antibodies in maternal serum.     

Gray platelet syndrome: selective alpha-granule deficiency and thrombocytopenia due to increased platelet turnover

Clinical and laboratory studies of two siblings, both suffering from gray platelet syndrome (GPS) are described. The patients had a mild bleeding disorder, their platelets were blue-gray in panoptic stains, and alpha-granules were markedly reduced, as shown by electron microscopy. The platelet content of platelet factor 4 and that of beta-thromboglobulin were significantly reduced (3%-7% of normal). Platelet count was decreased (33-150 X 10(9)/1) and small platelets were increased in platelet volume distribution. Bleeding time was prolonged on most occasions. Bone marrow aspiration was performed in one patient and revealed increased reticulin fibers, however, megakaryocyte count was normal. The mean platelet survival was 4.8 days using 111indium-labelled platelets. In this patient, platelet-associated IgG was within the normal range. Prednisone therapy failed to increase platelet count. Dental surgery was performed under cover of desmopressin and no bleeding complication occurred; however, no improvement of bleeding time was observed. The patient delivered a healthy male infant without hemorrhaging while under concurrent platelet transfusion therapy.     

Immunologic findings,thrombocytopenia and disease activity in lupus nephritis.

Twenty patients with nephritis due to systemic lupus erythematosus were followed up for a mean of 34 months after renal biopsy with serial determinations of total serum complement and C3 and C4 concentrations, binding of deoxyribonucleic acid (DNA), antinuclear antibody pattern and platelet count. There were 25 episodes of nonhematologic observed disease activity in 16 of the 20 patients; elevated DNA binding and thrombocytopenia correlated well with these episodes. The mean platelet count during episodes of observed disease activity was 96 +/- 42 X 10(9)/L, which was significantly different from the mean count of 248 +/- 90 X 10(9)/L during disease quiescence. The proportion of false-positive results with the immunologic tests varied from 25% to 67% and with platelet counts it was 11%. It is suggested that thrombocytopenia may be a simple and accurate index of disease activity in lupus nephritis.     

Neonatal autoimmune thrombocytopenia: role of high-dose intravenous immunoglobulin G therapy

High-dose intravenous immunoglobulin G (IVIgG) therapy results in a rapid reversal of thrombocytopenia in over 80% of children with acute immune thrombocytopenic purpura (ITP). Comparable results were observed in eleven infants with an analogous condition, neonatal autoimmune thrombocytopenia (NATP), who received IVIgG (2 g/kg body weight) administered alone (n = 6) or in combination with steroids (n = 5). The median platelet count pre-IVIgG therapy was 25 X 10(9)/l (range 5 to 74 X 10(9)/l). The overall response rate to IVIgG therapy, administered alone or in combination with steroids was 75% (12 of 16 treatment episodes). A good response to therapy was defined as an increase in the platelet count to greater than or equal to 50 X 10(9)/l and at least twice the pre-treatment value at 48 h after completion of the IVIgG infusion. The rapid and generally excellent response to IVIgG therapy in infants with NATP suggests that this treatment approach should be considered as first-line therapy for severely thrombocytopenic infants with this self-limiting but potentially serious disorder.     

Intravenous immunoglobulin (i.v. IgG) for previously treated acute or for chronic idiopathic thrombocytopenic purpura (ITP) in childhood: a prospective multicenter study

In a prospective multicenter study 42 thrombocytopenic (less than 30 X 10(9) platelets/l) children with chronic idiopathic thrombocytopenic purpura (ITP) or with acute ITP, dependent on or refractory to corticosteroids, were given 0.4 g i.v. IgG/kg body weight/day on 5 consecutive days and thereafter once a week if the platelet count fell to less than 20 X 10(9)/l or if the patient bled. After the initial 5 days of i.v. IgG the platelets rose within a mean of 7-8 days to greater than 30 X 10(9)/l in all and to greater than 150 X 10(9)/l in 33 of 42 patients (79%). After a mean observation time of 26.6 months 26 of 42 patients (62%) showed a satisfactory long-term effect, i.e. no need for treatment for at least 6 months without bleeding and with no platelet counts below 20 X 10(9)/l. No difference in response rate was found between children with chronic and those with previously treated acute ITP. These results indicate that i.v. IgG could be used to control emergency situations, e.g. to stop bleeding or to prepare a patient for surgery. I.v. IgG also represents a good alternative to treatment modalities, such as splenectomy and/or the administration of cytostatic immunosuppressants with potentially serious side effects. In addition to the expected transient rise in serum IgG levels, i.v. IgG induced a more prolonged elevation of serum IgM. Platelet associated IgG, elevated before therapy, was correlated with the clinical long-term outcome.     

Infectious syphilis in Canada in 1986.

Thirteen men with a median age of 37 (range 28 to 46) years who had extensive Kaposi''s sarcoma associated with acquired immune deficiency syndrome (AIDS) were treated with combination chemotherapy and alpha-interferon. Four patients had stage III disease and nine had stage IV disease (one with pulmonary and eight with gastrointestinal involvement). Treatment consisted of monthly courses of actinomycin D, 1 mg/m2, and vinblastine sulfate, 6 mg/m2, given intravenously on day 1, bleomycin, 10 mg/m2 given intravenously on days 1 and 8, and human lymphoblastoid (alpha-) interferon, 10 million U/m2 given subcutaneously three times a week for six doses starting on day 14. Forty-one treatment cycles (median 3, range 1 to 12) were administered. The median granulocyte and platelet counts on day 14 before the start of interferon therapy were 600 X 10(9)/L and 134 X 10(9)/L respectively; the counts did not fall further during interferon therapy. There was no difference in T-cell subsets, 2'',5''-oligoadenylate synthetase level or results of blastogenesis studies after interferon therapy. Four patients required admission to hospital for neutropenia-associated fever. A complete response (of 24 weeks'' duration) was seen in one patient and a partial response (of 14 to 44 weeks'' duration) in four. One patient had a mixed response, with regression of skin involvement but progression of pulmonary disease. The median length of survival was 48 (range 4 to 143) weeks. Eleven patients died of progressive Kaposi''s sarcoma, one of lymphoma and one of Pneumocystis carinii pneumonia. The results suggest that this form of therapy is not appropriate for patients with Kaposi''s sarcoma associated with AIDS.     

Limited usefulness of lymphocytopenia in screening for AIDS in hospital patients.

Lymphocytopenia is often present in patients with acquired immune deficiency syndrome (AIDS) and has been suggested as a useful screening test for AIDS. Of 625 patients consecutively admitted to an acute care university teaching hospital 91 (15%) were found to have a lymphocyte count of less than 1 X 10(9)/L, and 25 (4%) had a count of less than 0.5 X 10(9)/L. The corresponding figures for 32 patients at the hospital in whom AIDS had been diagnosed were 13 (41%) and 4 (13%). Absolute lymphocyte counts in hospitalized patients should not be used as the sole means of identifying patients at high risk for AIDS.     

Bleeding time in patients with hepatic cirrhosis.

OBJECTIVE--To determine the frequency of an abnormal bleeding time in patients with cirrhosis and to relate this to known factors that affect primary haemostasis and to the severity of liver disease. DESIGN--Prospective clinical and laboratory study in patients admitted for complications or investigations of liver disease. SETTING--Royal Free Hospital hepatobiliary and liver transplantation unit. SUBJECTS--100 Consecutive inpatients aged 17-74 with various forms of cirrhosis, including alcoholic, biliary, autoimmune, viral, and cryptogenic. At least 10 days had elapsed since any episodes of bleeding, resolution of sepsis, or alcohol intake. No patient was taking any drug known to affect primary haemostasis. MAIN OUTCOME MEASURES--Bleeding time as measured with the Simplate double blade template device. A bleeding time longer than 10 minutes was considered abnormal. Other measures were platelet count, prothrombin time, partial thromboplastin time, packed cell volume, and blood urea, serum bilirubin, and serum albumin concentrations, all measured on each subject at the same time by standard laboratory methods. RESULTS--A weak but significant correlation existed between the bleeding time and the platelet count (rs = 0.483; p less than 0.001). There were significantly lower platelet counts, longer prothrombin times, and higher blood urea and serum bilirubin concentrations in the 42 patients with bleeding times of 10 minutes or more compared with the 58 patients with bleeding times less than 10 minutes. Multiple linear regression analysis showed that the bilirubin concentration as well as the platelet count was independently correlated with the bleeding time. The combination of a platelet count greater than 80 x 10(9)/l and a prothrombin time less than 17 seconds (usually taken as safe limits for performing routine liver biopsy) did not predict a normal bleeding time. Ten of 39 patients fulfilling these criteria had a prolonged bleeding time. CONCLUSIONS--Prolonged bleeding time is common in patients with cirrhosis, even in those with prothrombin times and platelet counts within "safe limits" for invasive procedures. The severity of liver disease as assessed by the bilirubin concentration plays an important part in determining the bleeding time in cirrhosis. The bleeding time should be measured when assessing patients for invasive procedures who have a raised bilirubin concentration or poor hepatic function, even if the platelet count and prothrombin time are considered adequate.     

Platelet count and mean platelet volume in an Algerian population indicating a low prevalence of Mediterranean macrothrombocytopenia

Platelet count was 225 X 10(9)/l in 225 healthy male Algerians and 263 X 10(9)/l in 208 females. The mean platelet volume was 9.15 fl in the males and 9.30 in the females. The figures agree with those obtained in a British and an American population, but differed from those of an Australian population of immigrants from Mediterranean countries, essentially Italy and Greece. The prevalence of Mediterranean thrombocytopenia must therefore be low in Algeria.     

"Anti-platelet antibodies" in HIV infected haemophiliacs.

We have studied anti platelet antibodies and circulating immunocomplexes in 16 haemophiliacs with mild thrombocytopenia eight of which were infected by human immunodeficiency virus (HIV). No difference in platelet count was observed between HIV+ (143 +/- 31 x 10(9)/l) and HIV- patients (148 +/- 30 x 10(9)/l). On the contrary, HIV+ haemophiliacs had serum platelet bindable IgG (SPBIgG), normal platelet associated IgG (PAIgG), high serum IgG and circulating immunocomplexes (CIC). Considering all 16 patients serum IgG correlated with CIC (r = 0.7 p less than 0.01) and SPBIgG (r = 0.6 p less than 0.01) respectively. We obtained also a positive correlation between serum CIC and SPBIgG (r = 0.51 p less than 0.05). Immunoblotting of patients' sera showed no specific binding to target platelet antigens. In conclusion there is no evidence of HIV related immune thrombocytopenia in our haemophiliacs but the study confirms the appearance of immunocomplexes in the HIV+ subjects.     

ITP in pregnancy and the newborn: introduction

Idiopathic thrombocytopenic purpura (ITP) occurs more commonly in young women and is one of the commonest immune mediated disorders in pregnancy. It may exist as an incidental finding in an otherwise healthy pregnant woman or may be associated with symptomatic reduction in the platelet count and varying degrees of clinical hemorrhage. The condition termed incidental thrombocytopenia of pregnancy is invariably associated with a platelet count of greater than 100 x 10(9)/L and a very low incidence of fetal thrombocytopenia. Symptomatic thrombocytopenia is more commonly associated with low platelet counts in the fetus (estimated between 20%-40%). It has recently been suggested that the incidence of fetal thrombocytopenia is substantially lower than this figure. The management of ITP in pregnancy is complicated by the fact that fetal thrombocytopenia is difficult to diagnose and carries substantial risks during the delivery process with rare cases of fetal hemorrhage occurring spontaneously in utero. Unfortunately there are no laboratory studies that can be performed precisely in the mother that may predict the occurrence of fetal thrombocytopenia. Maternal management is usually directed towards treatment of maternal symptoms. Maternal treatment or response to treatment is inconsistently associated with predictable changes in the fetal platelet count. Obstetric management is aimed at reducing the risks of life threatening fetal hemorrhage occurring at the time of delivery, and fetal management is directed towards the obtaining of fetal platelet samples in order to plan an appropriate strategy for obstetrical delivery. Fetal blood samples are obtained either by a scalp vein puncture at the time of delivery or earlier in gestation by the use of the newer technique termed percutaneous umbilical blood sampling. Fetuses with platelet counts of less then 50 x 10(9)/L are generally delivered by cesarean section whereas those with counts greater than 50 x 10(9)/L are allowed to proceed with vaginal delivery assuming no obstetrical contraindications exist. The use of IVIgG therapy during pregnancy has theoretical implications on improving platelet counts in the mother in situations of severe hemorrhage, however cannot be considered to be appropriate treatment for the prevention of fetal thrombocytopenia, since the exogenous transport of IVIgG across the placenta appears to be inconsistent and unpredictable.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cytoreductive effect of recombinant alpha interferon in patients with myelofibrosis with myeloid metaplasia

In an attempt to reduce myeloproliferation, we administered recombinant alpha-2b interferon (r-alpha INF) to ten patients with myelofibrosis with myeloid metaplasia (MMM) in a hypercellular phase, as part of a phase II trial. Two patients experienced severe side effects and stopped treatment before completion of the first week. In the eight evaluable patients, r-alpha INF was given for 16 weeks at an initial dosage of 3 X 10(6) U/day, with monthly increments in the case of response failure, i.e. a decrease in WBC or platelet count of less than 25% of the initial value. Two cases responded at the starting dosage, while the effective dosage was 5 X 10(6) U/day in the others. At the end of the 16th week, Hb showed minor changes: from an initial value of 12.08 g/dl, range 8.3-17.3, to 11.6 g/dl, range 7.7-18 (P = 0.12); WBC were reduced from 54 X 10(9)/l, range 6.4-69.4, to 17.5 X 10(9)/l, range 5-39 (P = 0.09, 4/8 responses); platelets decreased from 775 X 10(9)/l, range 215-1748, to 403 X 10(9)/l, range 118-730 (P = 0.008, 8/8 responses). Minor changes in spleen size were also noted, while no significant changes in bone marrow fibrosis occurred. Influenza-like symptoms and fatigue were common side effects. In conclusion, r-alpha INF has a role as a non-leukemogenic cytoreductive agent in the therapy of MMM, especially for cases with thrombocytosis.     

Leukostasis associated with blood transfusion in acute myeloid leukaemia.

Three patients with acute myeloblastic leukaemia and blast cell counts greater than 100 X 10(9)/1 (100 000/mm3) died unexpectedly soon after blood transfusion. In two cases postmortem examination disclosed cerebral leukostasis. Analysis of the records from the MRC''s fourth and fifth acute myeloid leukaemia trials showed that in the first week after diagnosis mortality was five times greater in patients with blast counts above 100 X 10(9)/1 than in patients with lower counts. Age and platelet count did not explain this excess. The mean haemoglobin concentration in the patients with high blast counts who died within the first week was 10.5 +/- 2.8 g/dl, which was significantly higher than that in the surviving group (7.6 +/- 2.4 g/dl). Only half the patients received chemotherapy within two days of diagnosis. Leukostasis is an important cause of early death in patients with high blast counts, and the increase in viscosity produced by transfusing to a haemoglobin concentration above 10 g/dl may lead to sudden deterioration. Transfusion to such concentrations should be avoided until the blast count has been reduced by early chemotherapy.     

Recombinant interferon-alpha, but not interferon-gamma is effective therapy for essential thrombocythemia

Recombinant interferon-gamma with a starting dose of 0.5 mg 3x/week subcutaneously, was administered to 6 patients with essential thrombocythemia (median platelet count 1172 X 10(9)/l, range 602-1564). Four of the patients had received alkylating agents previously. Hematological remission, defined as a decrease in platelet counts to less than or equal to 350 X 10(9)/l, was observed in none of these patients. Subsequently 4 of these 6 patients, supplemented by 2 others were treated with interferon-alpha 2c at a dose of 5 X 10(6) U daily subcutaneously. Five patients showed hematological remission. In case of hematological remission the interferon-alpha doses was reduced to 5 X an thereafter to 3 X weekly 5 X 10(6) U. During an observation period ranging from 12-41 weeks platelet counts remained normal in all patients. Side-effects were mild and consisted of fever, myalgias, malaise and itching occurring mainly during the first month of treatment. No dose adaptation was required. The patients treated previously with interferon-gamma experienced the side effects from this drug less tolerably than those from the alpha-compound. These observations suggest that recombinant interferon-alpha may be an effective drug in treating essential thrombocythemia resulting in a sustained response.     

脐带间充质干细胞治疗儿童重型免疫性血小板减少症的探索性研究

目的探讨脐带间充质干细胞（UC-MSC）输注治疗儿童重型免疫性血小板减少症（s ITP）的疗效及安全性。方法采用UC-MSC治疗儿童s ITP 3例。发病年龄为3个月至4岁,初治时血小板计数为（1-7）×10^9/L,3例均为s ITP,均出现严重出血,激素及免疫抑制剂无效或依赖。后给予2-3次（1次/周）静脉输注非血缘UC-MSC,输注细胞量为（1-2）×10^6/kg。输注后密切监测血象及肝肾功能等各项指标,观察疗效及不良反应。结果随访时间15-45个月,3例在输注细胞后渐显效：第1例在输注细胞后20 d血小板达到65×10^9/L,随访4个月,血小板均维持在1×10^11/L以上;第2例在输注细胞后41 d血小板达105×10^9/L,之后血小板一直维持正常;第3例在输注第2次细胞后血小板渐上升至2×10^11/L以上。输注过程中1例出现面色发红,1例出现血压升高,随访至今无明显不良反应。结论 UC-MSC对儿童重型ITP有一定的疗效,能提高儿童的生活质量;有必要扩大病例数,进一步研究UC-MSC治疗儿童ITP的疗效及机制。     

Number of megakaryocytic progenitors and adhesion molecule expression of stem cells predict platelet engraftment after allogeneic hematopoietic stem cell transplantation

BACKGROUND: The mechanism of platelet recovery after hematopoietic stem cell transplantation and the factors that influence its time-course are not fully understood. Rapid hematopoietic recovery results in a reduction of transplantation-related complications. In the present study, we questioned and analyzed whether there were important factors predicting the speed of platelet engraftment. METHODS: Thirty-seven patients with various hematologic diseases transplanted with allogeneic BM between January 2002 and December 2005 were included. We investigated the differences in mononuclear cell counts (MNC), numbers of infused CD34(+), CD34(+) CD41(+) and CD34(+) CD61(+) cells and phenotypic analysis of homing-associated cell adhesion molecules (CXCR4, CD49d and CD49e). The number of megakaryocytes formed in vitro (colony-forming unit-megakaryocytes; CFU-Mk) was also measured. RESULTS: Median days of ANC >/=0.5x10(9)/L and platelet count >/=20x10(9)/L were 14.8 and 17.3, respectively. The number of infused CD34(+) CD41(+) and CD34(+) CD61(+) cells correlated much better with the time to platelet engraftment than that of infused CD34(+)cells (P<0.05 each). Rapid platelet recovery also occurred in patients receiving both higher homing-associated cell adhesion molecule doses and CFU-Mk (P<0.05 each). DISCUSSION: Rapid platelet recovery has several advantages, including reducing the cost of supportive therapy and reducing the risk of fatal bleeding as a result of severe thrombocytopenia. Our findings suggest that phenotypic and clonogenic assessment of infused progenitor cells can identify patients in whom platelet engraftment is likely to be significantly delayed, and new strategies to overcome related problems might be employed in the very near future.