ALBERT

Description: Fetal and neonatal immune thrombocytopenia (FNIT) is a life-threatening bleeding disorder, resulting from fetal platelet opsonization and destruction by maternal antibodies developed during pregnancy. The frequency of FNIT has been estimated at 0.5–1.5/1,000 liveborn neonates. However, the incidence of fetal mortality is currently unknown, as the rate of miscarriage in affected pregnant women has not been well studied. Integrin αIIbβ3 and Glycoprotein (GP) Ibα are major glycoproteins expressed on the platelet surface and are the two major antigens targeted by anti-platelet antibodies in autoimmune thrombocytopenia (ITP). However, it is unclear why the incidence of FNIT caused by anti-GPIbα antibodies is far lower than that of FNIT mediated by anti-β3 integrin antibodies. This difference cannot be well explained by the frequency of genetic polymorphisms of the two antigens. We hypothesized that: 1) GPIbα is less immunogenic, leading to less maternal antibody production during pregnancy, or 2) anti-GPIbα antibodies cause a less severe pathology, and thus have a lower chance of being reported, or 3) anti-GPIbα antibodies cause higher incidence of miscarriage, resulting in reduced reported cases. To test these hypotheses, the maternal immune response against fetal platelet GPIbα versus β3 integrin were compared in FNIT models, using syngeneic background BALB/c GPIbα−/− and β3−/− mice. The FNIT models were established by transfusing female GPIbβ −/− or α3−/− mice with 108 gel-filtered platelets from wild-type (WT) BALB/c mice weekly. After two platelet immunizations, flow cytometry assays were used to detect the titers of anti-GPIbα and anti-β3 antibodies, and the immunized females were bred with WT BALB/c male mice. We found that there was no significant difference in mean antibody titer between the two groups (P〉0.05). However, miscarriage occurred more frequently in anti-GPIbα-mediated FNIT (14/16 versus 8/16, P

Description: Gaucher disease (GD) is a lysosomal storage disorder characterized by anemia and thrombocytopenia, hepatosplenomegaly, and skeletal involvement. The management of Gaucher disease was improved by the development of enzyme replacement therapy (ERT). However, the bone response to ERT is generally slower compared to other clinical manifestations. Some have recommended the early use of ERT to prevent the development of severe skeletal complications. Because we have access to over 30 untreated patients in Ontario, we questioned the extent to which the bony complications progress in severity over a long period of time. We examined retrospectively the natural history of GD and the extent of skeletal manifestations in 22 untreated type 1 GD adult patients (mean age 49 ± 3.3, range of 20–81 years). Ten patients were N370S homozygotes and twelve were compound heterozygotes. The patients were followed for a median of 9.5 years (range of 3 to 16 years). Assessments included complete blood counts (CBC); levels of angiotensin converting enzyme (ACE), ferritin, and chitotriosidase; liver and spleen volumes; and occurrences of bony complications. Dual Energy X-ray Absorptiometry (DEXA), Magnetic Resonance Imaging (MRI) of femurs, skeletal survey, and plain radiography were utilized to assess bony complications in 21 patients. Hemoglobin (Hb) concentration did not significantly change over time (mean baseline concentration of 12.8 ± 0.27 g/dL vs mean recent concentration of 12.6 ± 0.37 g/dL, p = 0.65). Mean platelet count also remained relatively stable over time (mean baseline count of 138 ± 13 × 109/L vs mean recent count of 138.5 ± 18 × 109/L, p = 0.98). Mean ferritin and ACE concentrations were elevated and were stable over time. Liver volumes decreased over time (mean baseline liver volume of 1.2 × normal (N) vs mean recent volume of 1.06 × N, p = 0.27) and 6/21 (29%) patients had moderate hepatomegaly (liver volume ≥ 1.25 × N). Spleen volumes remained stable over time (mean baseline spleen volume of 6.4 × N vs mean recent volume of 5.1 × N, p = 0.56). None of the changes was statistically significant. Three of 19 (15.8 %) patients had moderate splenomegaly (spleen volume ≥ 5 × N), 2/19 (10.5%) had severe splenomegaly (spleen volume ≥ 15 × N), and 2/22 (9%) had splenectomy. The most common skeletal manifestations were infiltration of the bone marrow in 15/21 (71%) patients followed by osteopenia in 14/21 patients (67%), and infarctions in 6/21 (29%) patients. Other bony complications included osteoporosis in 3/21 (14%), avascular necrosis (AVN) in the left knee and femur in 1/21 (5%), and osteolysis in 1/21 (5%) patients; there were no cases of fractures. Three of 21 (14%) patients developed new infarcts (2N370S homozygous patients) over time, 1/21 (5%) developed AVN, and 4/21 (19%) had an increase in the degree of osteopenia. There were no significant differences observed between the N370S homozygous and compound heterozygous patients. Although GD and its skeletal complications progress in severity in some patients, our results suggest that GD complications including bony disease may stabilize over time. Therefore, early use of ERT may not be necessary in all type 1 GD patients.

Description: Gaucher disease (GD) is an inherited lysosomal storage disease, which is often managed by enzyme replacement therapy (ERT). While the response to ERT is gratifying in terms of hepatosplenomegaly, cytopenias, and general well-being, the response of bony disease is very slow, and in some cases non-existent. Skeletal manifestations are the most painful and debilitating components of GD type 1, and have a negative impact on the patient’s quality of life. Whether an increase in the dose of ERT has a beneficial effect, and whether substrate reduction therapy (SRT) stabilizes and/or ameliorates bony disease, is controversial. The aim of our study was to determine whether or not there is enough evidence to make a definitive statement about the effects of ERT and SRT on bony complications of Gaucher disease. We conducted a systematic review of all studies examining the effects of ERT and SRT on bony complications of Gaucher disease published before July 2008. The studies were identified by a computerized search using Medline, Embase, The Cochrane Database of Systematic Reviews, The Cochrane Central Register of Control Trials (CCTR), and bibliographies of papers subsequently retrieved from the search. Three hundred studies were grouped according to whether they deal with the natural history of GD or therapeutic issues and 17 studies were included in the review. Meta analyses were done using a random effects model and the studies compared baseline versus after-treatment values. Quantitative Chemical Shift Imaging (QCSI) of vertebral bone marrow (BM) fat fraction, Magnetic Resonance Imaging (MRI) T1-weighted signal, semi-quantitative MRI bone marrow burden (BMB) score, and bone mineral density (BMD) Z scores of spine and femur were used to assess the effects of ERT and SRT on bony complications. Of the 4 studies that measured BM fat fraction, 3 showed that fat fraction significantly increased after ERT (Weighted Mean Difference [WMD] of 0.17, 95 % CI of 0.13 to 0.2, n= 36, p 〈 0.00001) and one study showed a non-significant increase in fat fraction after SRT (n = 2, p = 1.23). MRI T1-weighted signal was measured in 6 studies (5 studies on ERT and one on SRT), and 44/78 (56%) of GD1 patients were responders to ERT versus 20/78 (25.6%) who did not respond to ERT. One study showed that BM infiltration generally decreased after SRT. Of the 3 studies that measured BMB score, 2 showed that BMB score significantly decreased after ERT (WMD of −4.98, 95 % CI of −8.38 to −1.57, n= 27, p = 0.004) and one study showed a stable BMB score after SRT (n = 6, p = 0.82).The 4 studies in which BMD Z score of lumbar spine (LS) was measured showed an increase in Z score after ERT (WMD of 0.37, 95 % CI of −0.05 to 0.79, n= 54, p = 0.09) and one study showed a significant increase in LS Z score after 6 months of SRT. Of the 3 studies that measured BMD Z score of femurs, 2 showed a non-significant increase in Z score after ERT (WMD of 0.16, 95 % CI of −0.29 to 0.61, n= 43, p = 0.48) and one study showed a significant increase in femur Z score after 6 months of SRT. These studies suggest that ERT may be more effective in ameliorating BM involvement than in increasing BMD Z scores. SRT may stabilize the BM involvement and generally increase the BMD Z scores. However, further investigations are needed on the effects of SRT on bony complications of GD.

Description: Background and hypothesis: Cyclosporine is administered to all patients undergoing allogeneic bone marrow transplantation in Hamilton. It is given intravenously at first then orally after engraftment. The manufacturer’s recommendation is to use a dose ratio of 1:3, IV to oral; the Hamilton unit uses a ratio of 1:2, yet has observed frequent rises of cyclosporine to toxic levels. We wished to confirm that the dose conversion ratio of 1:2 is associated with significantly high cyclosporine levels and nephrotoxicity. Methods and Results: Thirty-five consecutive patients undergoing allogeneic bone marrow transplantation at McMaster University Medical Centre were studied. We included patients who were diagnosed with a hematological cancer i.e. leukemia (76%), lymphoma (18%), or myelodysplastic syndrome (6%), and who underwent chemotherapy. The patients’ plasma cyclosporine levels were measured 4–5 days after its initiation and with every dose adjustment, and serum creatinine levels were measured daily. Forty four percent of the patients were males. In 53% of the patients 1:2 IV to oral conversion ratio caused elevation of plasma cyclosporine levels to the toxic range (p

Description: Fetal and neonatal alloimmune thrombocytopenia (FNAITP) is a life-threatening bleeding disorder which results from maternal anti-platelet antibodies that cross the placenta and destroy fetal platelets. In most cases FNAITP is mediated by anti-β3 integrin antibodies, whereas reported cases of anti-GPIbα mediated FNAITP are rare. This difference can not be solely explained by the frequency of their respective polymorphisms. It is unclear whether this is due to:the GPIbα antigen being less immunogenic, resulting in less maternal antibody generation during pregnancy, oranti-GPIbα antibodies mediating a less severe pathology, resulting in a reduced number of reported cases. To study the immunogenecity and antibody response to the GPIbα antigen, GPIbα deficient mice (GPIbα−/−, Black Swiss background) were transfused with wild-type (WT) platelets. No detectable anti-GPIbα IgG antibody was induced even after 8 transfusions (108 platelets/transfusion). This clearly differs from the immune response generated in β3 integrin deficient (β3−/−, BALB/c background) mice, in which anti-β3 integrin antibody can be easily detected after 2–4 WT platelet transfusions. This suggested that the MHC complex in Black Swiss mice might not be able to present the GPIbα antigen. We thus introduced the BALB/c background to the GPIbα−/− mice via backcrossing these mice with BALB/c mice for 9 generations (F9). To further minimize genetic background differences, the F9 BALB/c GPIbα−/− mice were bred with F9 BALB/c β3−/− mice to generate heterozygous BALB/c GPIbα+/− and β3+/− mice. These mice were subsequently used to generate littermate GPIbα−/− or β3−/− mice for the following studies. We found that BALB/c GPIbα−/− mice are immunoresponsive to the GPIbα antigen, but antibody titers after 2 and 4 platelet transfusions were significantly lower than those seen with the anti-β3 integrin model (1:50 & 1:200 vs 1:400 & 1:3200 respectively, P