The prevalence of platelet-specific antibodies in patients with HLA alloimmunization is very small. The search for concomitant platelet-specific antibodies would be indicated only when other causes of refractoriness to HLA-matched platelets are ruled out.

In recent years clinical factors have largely surpassed alloimmunization as the predominant cause of platelet refractoriness. This makes it necessary to properly identify and weigh the non-immune factors that have a major impact of refractoriness. A case-control study is suitable for such an analysis, and to our knowledge has not previously been performed to assess this issue. Fifty-two refractory patients were compared with 52 control patients who were transfused at the same time. Only one transfusion event was analysed per patient. Clinical and laboratory data were recorded at the time of selected transfusion, and their association with refractoriness was investigated by the contingency table method and the Cox stepwise logistic regression. There were 16 (31%) patients with HLA antibodies in the index group and only one in the control group. The corrected count increment in the group of patients refractory due to HLA antibodies was significantly lower than that in non-alloimmunized refractory patients [median (range): 48.5 (-3560, 4614) and 4058 (-4417, 6886), respectively; U = 493, P < 0.0001]. In the multivariate analysis, factors associated with refractoriness were the presence of HLA antibodies (odds ratio (OR) 50.7; 95% CI 5.5-463); fever (odds ratio 7.2; 95% CI 2.5-21) and BMT because of chronic myeloid leukaemia (odds ratio 7.3; 95% CI 1.8-30). The latter two were the only factors that remained independently associated with refractoriness after excluding alloimmunized patients and their controls. We conclude that HLA antibodies are strongly associated with platelet transfusion refractoriness, but account for less than a third of these patients. Fever and BMT because of chronic myeloid leukaemia were the only non-immune factors independently associated with refractoriness.

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Transfusion of cryopreserved HPCs carries a risk of serious adverse effects due to the use of DMSO. Some studies have shown that the incidence and severity of adverse reactions are dose related. 1 It is desirable therefore to reduce the amount of DMSO in cryopreserved components to minimize toxicity, particularly in children.The concentration of DMSO and the concentration of cells to be cryopreserved determine the volume and the amount of DMSO infused. Previous studies 2,3 describe satisfactory results using 5-percent DMSO or 3.5percent DMSO with HES. Also, high cell concentrations (up to 800 ‫ן‬ 10 6 /mL) in 10-percent DMSO have not shown a deleterious impact on function or engraftment of HPCs, either in vitro or in vivo. 4 Our approach used a high cell concentration (>200 ‫ן‬ 10 6 /mL) and a low DMSO concentration (5 percent) for cryopreservation. We report hematologic recovery in patients who received such transplants.HPCs were collected from 13 consecutive patients for autologous transplant. The cells were cryopreserved with 5-percent DMSO in autologous plasma as the only cryoprotectant at a final cell concentration equal to or greater than 200 ‫ן‬ 10 6 per mL. The cells were frozen at -80ЊC by immersion in a methanol bath in a mechanical freezer, 5 and stored at that same temperature. All patients were conditioned with myeloablative regimens and medicated with corticosteroids, antihistamines, and diuretics prior to transfusion of their thawed, unmanipulated HPCs.There were 6 boys and 7 girls with a median age of 11.8 years (range 4.5-19.2). Diagnoses were brain tumor in 5, Ewing sarcoma in 3, Hodgkin disease in 2, neuroblastoma in 1, T-cell acute lymphoblastic leukemia in 1, and Burkitt lymphoma in 1.The median volume of the cryopreserved HPCs and their cell concentrations were 300 mL (range, 134-700) and 263 ‫ן‬ 10 6 per mL (range, 192-390), respectively, with a median CD34+ cell content of 3.66 ‫ן‬ 10 6 per kg (range, 2.00-6.44). Median time from cryopreservation to transplantation was 10 days (range, 9-108).The median dose of DMSO infused was 0.41 mL per kg (range, 0.13-0.58) in an HPC component with a median volume of 8.2 mL per kg (range, 2.7-11.7). Adverse effects during transfusion were minimal. One patient experienced abdominal pain and vomiting and another required treatment for hypertension with nifidipine. If the HPCs had been cryopreserved by standard protocols (cell concentration 100 ‫ן‬ 10 6/ mL in 10 percent DMSO), the median volume of DMSO and HPC component transfused would have been 1.8 mL per kg (range 0.70-4.55) and 18 mL per kg (range 7-45), respectively.A granulocyte count > 0.5 ‫ן‬ 10 9 per L and a platelet count > 20 ‫ן‬ 10 9 per L were achieved after a median of 11 (range 10-14) and 12 (range 10-23) days, respectively. Hematologic recovery was adequate (Hb > 100 g/L, platelets > 100 ‫ן‬ 10 9/ L, and granulocytes > 1 ‫ן‬ 10 9/ L) in 9 of 12 evaluable patients at 3 months and in 9 of 10 evaluable patients at 6 months post-transplant. The only patient not achieving the target values was ...

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The case of a patient (Col) with multiple myeloma presenting as chronic cold agglutinin (CA) syndrome is reported. The CA (Col) was a monoclonal IgA/k paraprotein which recognizes an antigen fully expressed in adult and newborn erythrocytes, sialidase sensitive and partially resistant to proteases. Hemagglutination-inhibition studies showed that immunodominant N-acetylneuraminic acid bound alpha 2-->3 to O-glycans of glycophorins represents the CA(Col) epitope. These serological and biochemical findings fit with the anti-Sa specificity, of which only two previous examples are known. The clinical manifestations of CA (Col) were characterized by marked acrocyanosis, generalized livedo reticularis, and incapacitating dyspnea, but only mild hemolysis. Plasma-exchange therapy was effective in quickly removing the CA and relieving the associated clinical manifestations, but such benefit was only temporary. This is the first reported example of anti-Sa CA of IgA isotype and the first case of IgA CA syndrome treated by plasma exchange.