Clinical course of factor VIII inhibitors developed after exposure to a pasteurised Dutch concentrate compared to classic inhibitors in hemophilia A

After the introduction of a new pasteurised factor VIII concentrate (Factor VIII CPS-P) in The Netherlands in June 1990, an increase in the occurrence of inhibitors in hemophilia A patients was reported. The clinical course of this group of inhibitors (n = 12) was compared with hemophilia patients in whom an inhibitor developed before June 1990 (classic inhibitors) (n = 32). Striking differences were found between both groups not only in patient age (median 22 years versus 8 years) and number of exposure days (< 50 - > 1000 versus < 50), as described in previous reports, but also in clinical course and response to treatment. In the recent group of inhibitors antibody titers showed a rapid decline when product was changed which was not the case in the group with classic inhibitors. In the group of classic inhibitors immune tolerance therapy with low dose factor VIII succeeded in 83%. Success was to a high degree dependent on the inhibitor level. In the group of recent inhibitors immune tolerance with the same concentrate was only successful in a single patient. However, once the patients were switched to another concentrate, antibody levels dropped to less than 2 BU/ml within 8 months in all patients. It seems likely that in this group of product associated inhibitors, treatment success was due to elimination of antigen stimulation rather than induction of immune tolerance.

Platelet adhesion to collagen and endothelial cell matrix under flow conditions is not dependent on platelet glycoprotein IV

Platelet membrane glycoprotein IV (GPIV) is a cell-surface glycoprotein that has been proposed as a receptor for collagen. Recently, it has been shown that platelets with the Naka-negative phenotype lack GPIV on their surface, whereas donors with this phenotype are healthy and do not suffer from hematologic disorders. In this study, we compared Naka-negative platelets with normal platelets in adhesion to collagen types I, III, IV, and V and the extracellular matrix of endothelial cells (ECM) under static and flow conditions. No differences in platelet adhesion and subsequent aggregate formation on the collagens types I, III, and IV were observed under static and flow conditions. Adhesion of both homozygous and heterozygous Naka-negative platelets to collagen type V was strongly reduced under static conditions. Collagen type V was not adhesive under flow conditions. No difference in platelet adhesion to ECM was observed, which suggests that GPIV is not important in adhesion to subendothelium, for which ECM may serve as a model. These results indicate that GPIV is not a functional receptor for collagen under flow conditions.

Allogeneic bone marrow transplantation with a fixed low number of T cells in the marrow graft

Despite prophylaxis with immunosuppressive drugs, severe acute graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality in patients transplanted with unmodified bone marrow (BM) grafts from HLA-identical siblings. Although T-cell depletion of the BM graft has evolved as the most effective method to prevent severe acute GVHD, this beneficial effect is counterbalanced by an increased rate of graft failure and relapse of the disease. To find an approach to T-cell depletion that may avoid these extreme risks, we gave BM recipients a fixed low number of 1 x 10(5) donor T cells per kilogram of recipient's body weight in the graft. This corresponds with 99% T-cell depletion and is achieved by the addition of T cells to the graft that was previously depleted of T cells. A total of 70 patients with hematologic malignancies or aplastic anemia, including 40 patients with standard-risk leukemias, received BM grafts, depleted of T cells according to this approach, from HLA-identical siblings. The preparative regimen consisted of cyclophosphamide and total body irradiation. The patients also received a short course of cyclosporine posttransplant. Graft failure did not occur. Acute GVHD, only grade I or II, was seen in 70% of the patients and was limited to the skin in all patients. Chronic GVHD occurred in 31% of the patients and, with the exception of 1 patient, was limited to the skin as well. Relapse occurred in 3 of 40 (8%) patients with standard-risk leukemias, resulting in a projected survival at 5 years of 80%. Patients with standard-risk diseases had a procedure-related mortality of 11%. Quality of life, determined 1 year after BM transplant, was good in almost all patients with standard-risk diseases. Thus, this approach of T-cell depletion may be an approach that avoids the development of severe acute and chronic GVHD without damaging the function or antileukemic effect of the graft and that has a low transplant-related morbidity and mortality.

Large platelets continue to circulate in an activated state after myocardial infarction

This study was intended to investigate the actual platelet activation status after an acute coronary event. The activation status of circulating platelets was assayed directly by measuring the membrane activation markers CD62 and CD63 with the Düsseldorf III flow cytometry test in 22 patients with the diagnosis of acute myocardial infarction during the 48-h observation period following the acute event. The number of activated, marker-positive sample platelets was significantly increased in the post-MI patients: CD62: 5.8% x 2.25 +/- 1 vs. 3.5% x 2.32 +/- 1, P < or = 0.05; CD63: J8.7% x 1.77 +/- 1 vs. 4.6% x 2.16 +/- 1, P < or = 0.00.1. The platelet volume and count were concomitantly increased (12.1 +/- 2.4 fl/ 236 +/- 90 x 10(3) microliters-1 compared to 8.3 +/- 1.6 fl/ 187 +/- 42 x 10(3) microliters-1) in the control group. Particularly large platelets were identified as being activated documented by the exponential increase in the difference in CD63-binding sites per sample platelet above the 90%-percentile and below the 10%-percentile of the volume distribution: delta + 1341 +/- 903 (MI patients) vs. delta + 276 +/- 126 (controls), P < or = 0.00.1. Significant creatine kinase elevation and decrease in platelet count was found in the non-survivor subset (n = 5). We conclude that predominantly large platelets continue to circulate in an activated state after MI. This study provides direct evidence that the assumption of an increased thrombotic potential becomes operative in vivo in MI patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet adhesion to collagen types I through VIII under conditions of stasis and flow is mediated by GPIa/IIa (alpha 2 beta 1-integrin)

Platelet adhesion to fibrillar collagens (types I, II, III, and V) and nonfibrillar collagens (types IV, VI, VII, and VIII) was investigated in the presence of physiologic concentrations of divalent cations under conditions of stasis and flow. Under static conditions, platelet adhesion was observed to collagen types I through VII but not to type VIII. Under flow conditions, platelet adhesion to collagen types I, II, III, and IV was almost independent of shear rates above 300/s. Collagen type V was nonadhesive. Platelet adhesion to collagen type VI was shear rate-dependent and optimal at a rate of 300/s. Collagen types VII and VIII showed minor reactivity and supported platelet adhesion only between shear rates 100 to 1,000/s. Monoclonal antibody (MoAb) 176D7, directed against platelet membrane glycoprotein Ia (GPIa; very late antigen [VLA]-alpha 2 subunit), completely inhibited platelet adhesion to all collagens tested, under conditions of both stasis and flow. Platelet adhesion to collagen type III at shear rate 1,600/s was only inhibited for 85%. The concentration of antibody required for complete inhibition of platelet adhesion was dependent on the shear rate and the reactivity of the collagen. An MoAb directed against GPIIa (VLA-beta subunit) partially inhibited platelet adhesion to collagen. These results show that GPIa-IIa is a major and universal platelet receptor for eight unique types of collagen.

MDR-1 expression and response to vincristine, doxorubicin, and dexamethasone chemotherapy in multiple myeloma refractory to alkylating agents

PURPOSE

To assess whether the presence of enhanced multiple drug resistance (MDR)-1 gene expression in multiple myeloma (MM) patients predicts survival, as well as response to vincristine, doxorubicin, and dexamethasone (VAD) chemotherapy.

PATIENTS AND METHODS

Sixty-three MM patients refractory to alkylating therapy were studied. The presence of the MDR-1 gene product, a 170-kd glycoprotein (P-170), was analyzed in bone marrow plasma cells by means of the alkaline phosphatase (APAAP) technique using the P-170-specific monoclonal antibody (MoAb) C219. The prognostic value of MDR-1 gene expression, examined before VAD treatment, was compared with other established prognostic factors including beta 2-microglobulin, albumin, lactate dehydrogenase (LDH), and the plasma cell labeling index.

RESULTS

Fifty-nine percent of all samples were P-170-positive. No association could be demonstrated between response to VAD and MDR-1 gene expression (chi 2 P = .359), in contrast to high serum beta 2-microglobulin levels, which were positively correlated with response (P = .006). P-170-positive and -negative patients showed a median survival duration of 23 and 22 months, respectively, a difference that was not statistically significant (P = .9). beta 2-microglobulin, LDH, albumin, and the plasma cell labeling index were all significantly correlated with survival.

CONCLUSION

These results indicate that other mechanisms of resistance must be involved in MM apart from MDR. The role of MDR status at this stage of disease may be biased by the major contribution of dexamethasone to induction of response by VAD in MM patients.

Platelet adhesion to cyanogen-bromide fragments of collagen alpha 1(I) under flow conditions

The aim of this investigation was to identify domains of collagen type I that can support platelet adhesion under flow conditions. Four cyanogen bromide (CB) fragments composing 87% of the collagen alpha 1(I)-chain were studied under static and flow conditions. Under static conditions, bovine and human collagen fragment alpha 1(I)CB3 induced aggregate formation, whereas alpha 1(I)CB7 and alpha 1(I)CB8 supported adhesion of dendritic and contact platelets. Bovine alpha 1(I)CB6 weakly supported platelet adhesion. At shear rate 300/s, collagen fragment alpha 1(I)CB3 strongly supported platelet adhesion, whereas lower platelet adhesion was observed to alpha 1(I)CB7 and alpha 1(I)CB8. The fragment alpha 1(I)CB6 did not support platelet adhesion under flow conditions. Adhesion to alpha 1(I)CB3 was completely inhibited by a low concentration (0.6 IgG microgram/mL) of anti-GPIa monoclonal antibody (MoAb), whereas this concentration of antibody partially inhibited adhesion to alpha 1(I)CB7 and alpha 1(I)CB8. At higher concentrations (3 micrograms/mL) the anti-glycoprotein Ia (GPIa) antibody completely inhibited adhesion to alpha 1(I)CB8 and further reduced adhesion to alpha 1(I)CB7. Platelet adhesion to alpha 1(I)CB3, alpha 1(I)CB7, and alpha 1(I)CB8 was strongly inhibited by an anti-GPIb MoAb. A MoAb against the GPIb-binding site of von Willebrand factor (vWF) strongly inhibited platelet adhesion to alpha 1(I)CB7 and alpha 1(I)CB8, whereas platelet adhesion to alpha 1(I)CB3 was not inhibited. We conclude that under flow conditions alpha 1(I)CB3, alpha 1(I)CB7, and alpha 1(I)CB8 support GPIa/IIa-dependent platelet adhesion. The GPIb-vWF interaction is important under flow conditions for adhesion to alpha 1(I)CB7 and alpha 1(I)CB8 and probably also to alpha 1(I)CB3.

Patients with antiphospholipid antibodies and venous thrombosis should receive long term anticoagulant treatment

OBJECTIVE

To determine whether the finding of antiphospholipid antibodies in patients with venous thromboembolic episodes should influence the duration of treatment with anticoagulant drugs by mouth.

METHODS

A retrospective study was carried out in 19 patients with antiphospholipid antibodies and a history of venous thromboembolic episodes. The median follow up from the first venous thromboembolic episode was 93 months and the median age at this episode was 26 years. The patients had in total 34 venous thromboembolic episodes. The total follow up period comprised 32 periods with and 23 periods without anticoagulant drugs.

RESULTS

The probability of being free of recurrent venous thromboembolic episodes, calculated by the Kaplan-Meier method, was significantly influenced by the use of anticoagulant drugs. Patients receiving oral anticoagulants had at eight years a 100% probability of survival without recurrence, whereas patients in whom anticoagulant drugs were stopped had a 50% probability of a recurrent venous thromboembolic episode at two years, and a 78% probability of recurrence at eight years.

CONCLUSION

Patients with venous thromboembolic episodes and antiphospholipid antibodies have a high risk for recurrent venous thromboembolic episodes and long term treatment with anticoagulant drugs by mouth is an effective prophylaxis.

Aggregate formation is more strongly inhibited at high shear rates by dRGDW, a synthetic RGD-containing peptide

The effect of D-Arg-Gly-Asp-Trp (dRGDW), a synthetic RGD-containing peptide, on platelet adhesion and aggregate formation on various purified adhesive proteins and the extracellular matrix of endothelial cells was investigated with anticoagulated blood recirculating through a parallel-plate perfusion chamber. Aggregate formation on the extracellular matrix of phorbol myristate acetate (PMA)-stimulated endothelial cells and on collagen type I was more strongly inhibited by dRGDW at higher shear rates than at a low shear rate. Platelet adhesion to the extracellular matrix of nonactivated and PMA-stimulated endothelial cells was inhibited by dRGDW, especially at high shear rates, probably as a consequence of the inhibition of platelet spreading. Inhibition by dRGDW of platelet adhesion to von Willebrand factor, fibronectin, and fibrinogen was almost complete, indicating that platelet adhesion to these substrates is mediated through RGD-directed receptors. Platelet adhesion to laminin was not inhibited by the peptide, whereas platelet adhesion to collagen was increased as a consequence of the inhibition of aggregate formation. Our results show that dRGDW is a strong inhibitor of platelet adhesion and aggregate formation, especially at high shear rates.

Platelet membrane activation markers are predictive for increased risk of acute ischemic events after PTCA

BACKGROUND

We wished to investigate whether platelet activation is related to the clinical outcome during the 24 hours immediately after elective percutaneous transluminal coronary angioplasty (PTCA).

METHODS AND RESULTS

In 102 patients with high-grade coronary stenosis admitted for elective PTCA, preprocedural platelet activation was characterized by flow cytometric measurement of the proteins CD62, CD63, and thrombospondin expressed on the platelet surface membrane. The prevalence of acute ischemic events during the 24 hours immediately after the procedure was then related to the pre-PTCA platelet activation status. Fifty-six patients were classified as "nonactivated," whereas 46 patients showed an increased percentage of activated platelets. Two patients developed acute occlusion (1.96%) and four patients high-grade restenosis (3.92%), as confirmed by second-look coronary angiography. All events occurred in patients classified as "activated" (six of 46, or 13%). None of these patients received beta-blocker medication, which was associated with lower expression of platelet membrane activation markers. In the nonactivated patient group, no clinical events were found (0 of 56, or 0%). This difference in prevalence is significant (p = 0.007).

CONCLUSIONS

We conclude that analysis of platelet membrane activation markers may help to predict an increased risk of acute ischemic events after angioplasty.

A sudden increase in factor VIII inhibitor development in multitransfused hemophilia A patients in The Netherlands. Dutch Hemophilia Study Group

The development of antibodies to factor VIII (inhibitors) in response to clotting-factor concentrates administration in hemophilia is common during the first few years of treatment but rare in multitransfused patients. We have investigated the possible association of a recently introduced factor VIII concentrate (Factor VIII CPS-P) in The Netherlands with the occurrence of inhibitors. To this effect, we conducted two studies. First, we performed a national multicenter study in which clinical information and inhibitor test results were obtained for 447 hemophilia A patients over the period 1988 through 1991. Secondly, for a baseline comparison we estimated the frequency of inhibitor development in a closely followed cohort of 144 patients, from 1984 through 1989. Before the introduction of Factor VIII CPS-P, the incidence of new inhibitors was 4.4/1,000 patient-years in the national study from March 1988 through May 1990, and 3.9/1,000 patient-years in the cohort followed from 1984 through 1989. These figures are similar to the incidence of new inhibitors that was found in a large cohort of patients in the United States followed in the 1970s. In the period that the new concentrate Factor VIII CPS-P was on the market, from June 1990 through November 1991, 11 clinically relevant inhibitors were detected, which yielded an incidence over this interval of 20.1/1,000 patient-years, a 4.5-fold increase compared with the previous interval (C195: 1.4 to 14.3). Nine of these 11 patients had in their lifetime received over 250 infusions with factor VIII preparations. whereas all of the inhibitors detected in the previous time interval, and all of the 24 inhibitor patients described in the US study, had received less than 250 infusions in their lifetime. All patients who developed inhibitors after June 1990 had been exposed to Factor VIII CPS-P, whereas only 75% of the patients who did not develop an inhibitor had been exposed to this product. In a prospective extension of the study, with a second inhibitor measurement after 3 months, we found that one additional inhibitor had developed during 52.5 patient-years of Factor VIII CPS-P use. In conclusion, there has been a sudden increase in the frequency of inhibitor patients, for a large part among multitransfused patients. It seems more than likely that this increase is associated with the introduction of a new factor VIII concentrate in The Netherlands.(ABSTRACT TRUNCATED AT 400 WORDS)

Ultraviolet-B irradiation of platelets induces a dose-dependent increase in the expression of platelet activation markers with storage

Ultraviolet B (UVB) irradiation of platelet concentrates (PCs) has been proposed as a novel technology to prevent HLA sensitization. We have recently reported that 2 J/cm2 of UVB radiation abolishes alloreactive lymphocyte responses in vitro. In order to increase the efficacy of UV irradiation for the prevention of HLA sensitization, we exposed PCs to 4 or 8 J/cm2 of UVB and evaluated the effect of UV radiation on platelet integrity during storage. We report here that UV exposed platelets show a progressive increase in the expression of activation markers P-selectin (GMP-140; CD62) and LIMP-CD63 (GP-53; CD63) on the platelet membrane over time in a dose-dependent manner compared to age-matched controls. Platelet metabolism was also enhanced as evidenced by significant changes in lactate and pH during post-irradiation storage. Based on these findings we transfused PCs within 4 h after UV irradiation. PCs exposed to 4 J/cm2 showed normal post-transfusion recoveries and haemostatic functions, while poor platelet recoveries were found after administration of PCs exposed to 8 J/cm2. We hypothesize that the rapid expression of P-selectin on platelets exposed to the higher dose of UVB leads to an increased binding of these platelets to leucocytes in the circulation resulting in poor platelet recoveries.

Comparison of platelet membrane markers for the detection of platelet activation in vitro and during platelet storage and cardiopulmonary bypass surgery

Changes in the platelet plasma membrane during activation were investigated by flow cytometry in a comparative study of in vitro platelet activation during platelet storage and cardiopulmonary bypass surgery. We studied changes in the expression of the plasma membrane glycoproteins lb and llla and CD31 antigen (PECAM-1), the alpha-granule membrane proteins GMP-140 (PADGEM, CD62 antigen) and GMP-33, and lysosomal integral membrane protein-CD63. A simultaneous change in the expression of the various glycoproteins induced by platelet activation was seen after thrombin stimulation in vitro and during platelet storage. Platelet activation in vivo in patients showed a more complex change in the expression of membrane glycoproteins. During cardiopulmonary bypass the mean fluorescence values for glycoprotein llla, GMP-33, and the percentage of GMP-140 and lysosome integral membrane protein-CD63 expressing platelets increased significantly. CD31 antigen expression was significantly decreased, whereas glycoprotein lb expression did not change. We conclude that flow cytometry is useful for the detection of changes in the expression of membrane glycoproteins induced by platelet activation in vitro and during platelet storage. Application of flow cytometry as clinical tool for screening platelet activation in patients or for identification of a prethrombotic state requires evaluation of a panel of platelet membrane glycoproteins because the changes in membrane expression may be different in various clinical situations.

Increased thromboxane biosynthesis in patients with acute cerebral ischemia

BACKGROUND AND PURPOSE

Clinical and experimental studies suggest that platelets have a major role in the pathogenesis of cerebral ischemia. However, ex vivo both platelet aggregation studies and measurements of platelet-derived products in patients with cerebral ischemia have shown inconsistent results. The present study was designed to resolve this inconsistency.

METHODS

We have measured the urinary excretion of a thromboxane metabolite, 11-dehydro-thromboxane B2, by a previously validated radioimmunoassay technique in 51 patients with acute cerebral ischemia who had experienced either a transient ischemic attack (14 patients) or an ischemic stroke (37 patients) and in 20 control patients with nonvascular neurological disorders. The median time between the onset of symptoms and urine sampling was 24 hours (range, from 2 hours to 8 days).

RESULTS

The excretion rate of immunoreactive 11-dehydro-thromboxane B2 ranged between 39 and 478 pmol/mmol creatinine in patients with a transient ischemic attack and between 23 and 5,916 pmol/mmol creatinine in stroke patients, with 29% (p = 0.18) and 51% (p = 0.004) of the urine samples, respectively, exceeding the upper limit of the control samples (251 pmol/mmol creatinine [mean +/- 2 SD]) (p = 0.01). In stroke patients, metabolite excretion was not related to the type (cortical or "lacunar") or site of cerebral infarction. Low-dose aspirin (50 mg per day for 7 days) reduced the urinary excretion by approximately 85% in 11 consecutive stroke patients.

CONCLUSIONS

We conclude that 1) episodes of enhanced thromboxane biosynthesis are detected infrequently in patients with a transient ischemic attack, 2) aspirin-suppressible episodes of increased thromboxane formation can be detected during the early phase of acute ischemic stroke, and 3) this finding may provide a rationale for testing the efficacy and safety of this drug in this setting.

Salvage therapy with ProMACE-MOPP followed by intensive chemoradiotherapy and autologous bone marrow transplantation for patients with non-Hodgkin's lymphoma who failed to respond to first-line CHOP

PURPOSE

We used alternative chemotherapy immediately followed in early-response patients by high-dose chemoradiotherapy and autologous bone marrow transplantation (ABMT) to treat patients with non-Hodgkin's lymphoma (NHL) who had failed to respond to first-line chemotherapy.

PATIENTS AND METHODS

Thirty-one patients with NHL of intermediate- or high-grade malignancy who had failed to respond to first-line cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy were treated. Seventeen patients had primary refractory disease and 14 had relapsed from first complete response (CR). The treatment consisted of prednisone, methotrexate, doxorubicin, cyclophosphamide, etoposide, mechlorethamine, vincristine, and procarbazine (ProMACE-MOPP) salvage chemotherapy, followed, in case of responsive disease (at least partial response [PR]), by high-dose cyclophosphamide and total-body irradiation (TBI) with ABMT.

RESULTS

Twenty-eight of 31 (90%) patients achieved PR (23 patients) or CR (five patients) with ProMACE-MOPP, and three failed to respond. Seventeen of 28 (61%) patients who responded underwent the ABMT procedure, which resulted in CR in 14 patients (82%); three failed to respond. Eleven responsive patients were not transplanted because of residual bone marrow infiltration (five patients), patient refusal (four patients), and ProMACE-MOPP-related mortality (two patients). To date, nine patients are alive and in CR, seven with a median follow-up of 41 months (range, 17 to 84 months). Referring to the original CHOP treatment, five of 17 (29%) patients with primary refractory disease remain free of disease at a median of 36 months after ABMT, and four of 14 (29%) patients in first relapse remain free of disease at a median of 33 months after ABMT. One patient died of AMBT-related toxicity.

CONCLUSION

ProMACE-MOPP salvage chemotherapy produces a high early-response rate in patients who fail to respond to first-line CHOP, and more than half of the responding patients can be scheduled to receive ABMT, resulting in disease-free survival (DFS) at 3 years in 50% of the transplanted patients and in 25% of the original number of patients intended to receive this treatment.

A prospective, controlled multicenter study on the obstetric risks of pregnant women with antiphospholipid antibodies

OBJECTIVES

A prospective, controlled multicenter study was performed to estimate the obstetric risks of antiphospholipid antibodies (the lupus anticoagulant and anticardiolipin antibodies). In addition, the risks of prior thrombosis, obstetric history, systemic lupus erythematosus, and high-dose prednisone treatment were evaluated.

STUDY DESIGN

After screening for antiphospholipid antibodies in patients with lupus erythematosus or women with prior fetal loss(es), 59 subsequent pregnancies with and 54 without these antibodies were followed.

RESULTS

The presence of the lupus anticoagulant and a history of at least three spontaneous abortions could predict fetal loss (p = 0.032 and 0.001, respectively). In live born infants, a low birth weight could be predicted by the presence of anticardiolipin antibodies (p = 0.034), prior intrauterine fetal death (p = 0.025), and treatment with high-dose prednisone (p = 0.002). No relationships were seen between antiphospholipid antibodies and small-for-gestational-age newborns and pregnancy-induced hypertension or preeclampsia. The disappearance of antiphospholipid antibodies during pregnancy was not correlated with live birth.

CONCLUSION

It is concluded that the presence of antiphospholipid antibodies is a risk factor for adverse pregnancy outcome.

Autologous bone marrow transplantation for adult poor-risk lymphoblastic lymphoma in first remission

PURPOSE

Adult patients with poor-risk lymphoblastic lymphoma (LBL) treated with intensive multiagent chemotherapy (acute lymphoblastic leukemia [ALL]-like regimens) have a poor prognosis, with a disease-free long-term survival rate of less than 20%, caused by a very high relapse rate. Thus, adult patients with poor-risk LBL are candidates for alternative intensive consolidation therapy.

PATIENTS AND METHODS

Nine adult patients with poor-risk LBL in first remission after treatment with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP; six patients) or ALL-like regimens (three patients), were treated with high-dose cyclophosphamide and total body irradiation (TBI) followed by nonpurged autologous bone marrow transplantation (ABMT).

RESULTS

Two of nine patients relapsed at 4 and 8 months, respectively, after BMT, and one patient died of acute myeloblastic leukemia (AML) 7 months after ABMT without recurrence of his lymphoma. Six patients are in unmaintained first remission with a follow-up of 12 to 113 months (median, 53 months) after transplantation.

CONCLUSIONS

These results suggest that intensive consolidation therapy with high-dose cyclophosphamide and TBI followed by nonpurged ABMT may improve the long-term prognosis of this disease.

Identification of a 33-Kd protein associated with the alpha-granule membrane (GMP-33) that is expressed on the surface of activated platelets

To identify antigens on the platelet plasma membrane that are exposed after activation, we developed a monoclonal antibody (MoAb) designated RUU-SP 1.77. The RUU-SP 1.77 antigen is present on the membrane of resting platelets at a basal level and is strongly expressed on the plasma membrane after thrombin activation. Freshly fixed platelets bound 4,150 +/- 1,935 (mean +/- SD) RUU-SP 1.77 molecules per platelet; on fixed thrombin-stimulated platelets the number of binding sites was upregulated to 19,050 +/- 5,120 (kd 4.5 +/- 0.8 nmol/L). MoAb RUU-SP 1.77 recognized a major protein of 33 Kd and a minor 28-Kd protein, both under nonreduced and reduced conditions. Immunoelectron microscopic studies showed the presence of the protein associated with the membrane of alpha-granules. Due to the localization associated with the alpha-granule membrane, we have designated it GMP-33 (granule membrane protein with a molecular weight of 33 Kd). Based on structural properties, we conclude that GMP-33 is a protein associated with the alpha-granule membrane that has not been described before.

Biochemical characterization of PECAM-1 (CD31 antigen) on human platelets

The platelet plasma membrane expresses several membrane glycoproteins with a high molecular weight. In this study we have investigated the properties of the CD31 antigen on platelets and endothelial cells using the monoclonal antibody (MoAb) RUU-PL 7E8. Comparative studies revealed that the CD31 antigen, PECAM-1 and endoCAM are the same protein. The CD31 antigen was immunoprecipitated with a molecular mass of 125 kDa nonreduced and 135 kDa reduced from Nonidet-P40 lysates of surface labeled human platelets. The relative position in two-dimensional nonreduced/reduced SDS-PAGE and IEF-PAGE, compared to other glycoproteins of similar molecular weight, was elucidated. The position of the CD31 antigen was clearly distinct from the position of the platelet membrane glycoproteins Ia, Ib, IIa, IIb, IIIa and the granule membrane protein GMP-140. Native resting platelets bound 7,760 +/- 1,670 molecules/platelet, whereas thrombin-stimulated platelets bound 14,500 +/- 3,790 molecules/platelet. Immunoelectron microscopy revealed the presence of the CD31 antigen on the membrane of both resting and thrombin-activated platelets. Immunofluorescence studies showed the presence of the CD31 antigen in the membrane of endothelial cells on sites of cell-cell contact, suggesting that the CD31 antigen might be involved in cell-cell interaction. In functional studies, MoAb RUU-PL 7E8 did not inhibit platelet aggregation, platelet adherence to the extracellular matrix of endothelial cells and purified collagen fibrils under flow conditions, nor was any influence found on endothelial cell detachment and growth.

Identification of risk factors for bleeding during treatment of acute venous thromboembolism with heparin or low molecular weight heparin

In a prospective double-blind trial, we treated 194 patients with acute venous thromboembolism with heparin or low molecular weight heparin (LMWH; Fragmin). To evaluate the most important prognostic factors for bleeding, the presenting clinical features of the patients, the patients' anticoagulant responses, and the doses of the drugs were analyzed using univariate and multivariate regression analyses. No significant differences in clinical risk factors associated with bleeding were observed between heparin and LMWH. The univariate analyses ranked the parameters in the following order of importance: World Health Organization (WHO) performance status, history of bleeding tendency, cardiopulmonary resuscitation, recent trauma or surgery, leukocyte counts, platelet counts, duration of symptoms, and body surface area. Patients with WHO grade 4 had an eightfold increase in risk of bleeding as compared with WHO grade 1. Assessment of the individual contribution of each variable using multivariate regression analysis showed that the WHO performance status was the most important independent factor predicting major bleeding. A history of a bleeding tendency, recent trauma or surgery, and body surface area were also independent risk factors. The risk of bleeding was influenced by two factors related to the treatment, the patient's anticoagulant response as measured with the anti-Xa assay and the dose of the drug expressed as U/24 h/m2. An increased risk of bleeding was only observed at mean anti-Xa levels greater than 0.8 U/mL for both drugs. Significantly more major bleedings occurred in patients treated with high doses of the drugs, an observation that was independent of the concomitant anti-Xa levels. It should be considered whether choosing an appropriate initial dose adapted to the patient's body surface area and clinical risk factors can improve the efficacy to safety ratio of heparin treatment.

Large platelets circulate in an activated state in diabetes mellitus

Diabetes mellitus is associated with aggravated development of vascular complications. Yet, it has not been established whether platelet hyperreactivity contributes as a pathogenetic factor. In order to study the role of activated platelets in diabetes mellitus, we investigated the expression of the membrane activation markers CD63 (GP53) and CD62 (GMP-140) as direct indicators of in vivo activation. The CD63-positive fraction was significantly higher in patients (6.1% X 3.7 +/- 1) than in controls (2.7% X 3 +/- 1). In parallel, the CD62-positive fraction was significantly elevated in patients to 5% X 2.5 +/- 1 in comparison to controls (3% X 2 +/- 1). Patients with angiopathy had a mean increase of 304% in CD63-positive and of 223% in CD62-positive platelets. Patients without clinically detectable angiopathy showed a trend to an increased fraction in CD63-/CD62-positive platelets. There was no correlation of the activation markers with fasting blood glucose, HbA1 or platelet count. CD63 platelet bound fluorescence significantly increased with platelet size in the patient group. We conclude that in diabetes mellitus an increased number of large platelets circulate in an activated state predominantly in patients with angiopathy. This could imply that platelets become activated by vascular lesions. The trend in patients without vascular disease, however, suggests that activated platelets may also basically contribute to the prethrombotic state in diabetes mellitus.

Cytomegalovirus infection causes delayed platelet recovery after bone marrow transplantation

The pathogenic effect of cytomegalovirus (CMV) infection on the hematopoietic recovery after bone marrow transplantation (BMT) was retrospectively studied in 87 recipients of (nonpurged) autologous BMT and in 56 recipients of allogeneic BMT from HLA-identical siblings. Indications for autologous BMT were lymphomas or acute leukemias and for allogeneic BMT various malignancies or aplastic anemia. Patients were divided for the study in two groups, CMV-positive and CMV-negative on the basis of the CMV status pretransplant, and CMV-negative patients were kept CMV-negative by the local transfusion policy. In allogeneic BMT recipients, platelet recovery was significantly slower in CMV-positive patients than in CMV-negative patients (platelets greater than 50,000 cells/microL after 41 days v 27 days, P = .007). This difference held true when patients with acute graft-versus-host disease above grade I were excluded (platelets greater than 50,000 cells/microL after 42 days v 24 days, P = .01). In autologous BMT, the negative effect on platelet recovery was present in patients with lymphomas, but absent in patients with acute leukemias. Patients with acute leukemias had a very delayed recovery of platelets and granulocytes after autologous BMT, irrespective of the CMV status, probably due to the original stem cell disorder. Platelet recovery was significantly slower in CMV-positive autologous BMT recipients with lymphomas than in those not infected (platelets greater than 50,000 cells/microL after 36 days v 24 days, P = .0002). The presence of CMV infection had no effect on the recovery of granulocytes in autologous or allogeneic BMT. These data show that CMV infection causes delayed platelet recovery after BMT; however, in autologous BMT, the underlying disease (ie, acute leukemia) is more determinant for hematopoiesis after BMT.