Endogenous serum thrombopoietin (TPO) levels were measured in 31 patients with aplastic anaemia (AA) using an enzyme immunoassay with a sensitivity of 20 pg/ ml. The median platelet count for all AA patients was 30 +/- 29 x 10(9)/l (range 5-102) compared with a median of 284 +/- 59 x 10(9)/l (range 148-538) for normal controls. Serum TPO levels were significantly elevated in all patients compared with normals (1706 +/- 1114.2, range 375-5000 v 78 +/- 54, range 16.5-312.9, P < 0.0001). There was no correlation between serum TPO levels and the degree of thrombocytopenia in AA patients, but TPO levels were significantly higher in patients who were platelet transfusion dependent than in patients who were transfusion independent (P < 0.01). There was a trend for higher TPO levels in patients with severe AA compared with non-severe AA patients. Clinical trials of TPO and a related truncated, pegylated molecule, megakaryocyte growth and development factor (PEG-rHuMGDF), are awaited to determine whether treatment with these drugs will result in increased platelet counts in patients with AA.

Summary. Seven patients with B-cell leukaemia -six with chronic lymphocytic leukaemia (CLL) and one with B-prolymphocytic leukaemia (B-PLL) -were treated with CAMPATH-1H*, a genetically reshaped CD52 monoclonal antibody, administered subcutaneously (s.c.) three times a week for 6-12 weeks. Four were resistant to, and three had had a short partial remission (PR) following, fludarabine chemotherapy. The patient with B-PLL achieved complete remission and three patients with CLL attained PR; two of the latter were retreated. The three remaining patients were non-responders. Three patients were transfusion-dependent before CAMPATH and all three became transfusion-independent after treatment. The overall median survival from starting CAMPATH-1H was 11 months. Three patients reactivated cytomegalovirus (CMV) during the course of treatment, and two were treated with, and responded to, ganciclovir.

Recognition of thrombosis as a complication of exposure to high altitude has stimulated interest in rheological changes resulting from hypobaric hypoxia. Previous studies of platelet counts at high altitude have yielded conflicting results and have not been studied in conjunction with potential mediating cytokines. We studied the effects of high-altitude exposure on platelet numbers, thrombopoietin (tpo) and erythropoietin (epo) levels in man. A group of 28 volunteers from the Bolivian Airforce stationed at Santa Cruz (600 m altitude) were studied 48 h and 1 week after their ascent to La Paz (3600 m). In addition 105 volunteers based at Santa Cruz for at least 1 year were compared with 175 age- and sex-matched residents at El Alto (4200 m). Platelet counts were measured immediately after sampling and serum samples assayed for tpo and epo. In the ascending group, mean platelet counts were 251 x 10(9), 367 x 10(9) and 398 x10 (9)/l at 600 m and following 48 h and 1 week at 3600 m respectively. Mean tpo levels were 132.5, 76 and 92 pg/ml with epo values of 2.98, 11.6 and 7.9 mIU/ml respectively. In the resident populations mean platelet counts were 271 x 10(9)/l in the low- and 471 x 10(9)/l in the high-altitude groups. Mean tpo and epo levels measured 69.3 pg/ml and 4.5 mIU/ml respectively at 600 m and 58.5 pg/ml and 5.1 mIU/ml at 4200 m. In conclusion we have demonstrated a significant and sustained elevation in platelet numbers within 48 h of ascent to high altitude. Our findings do not support a role for tpo as a mediator of the increased platelet count. However, these data do not discount epo as a potential candidate.

A regimen combining fludarabine, cyclophosphamide and mitoxantrone (FCM) was used to treat 29 patients with relapsed or refractory chronic lymphocytic leukemia (CLL, N = 24) and low-grade non-Hodgkin's lymphoma (NHL, N = 5) based on evidence suggesting synergism between the 3 drugs. Patients were treated with mitoxantrone 5mg/m2 i.v. day 1 only, fludarabine 25 mg/m2 i.v. for 3 days or 24 mg/m2 orally for 5 days, cyclophosphamide 250 mg/m2 i.v. for 3 days or 150 mg/m2 orally for 5 days inclusive. Eighteen patients had previously received fludarabine and most were heavily pretreated with 40% having >2 prior treatments. A median number of 4 FCM courses (range of 1-9) were given. The response rate was 78.5%: 32% complete remission, 25% nodular partial remission, 21.5%, partial remission. Median duration of response was 19 months and median survival was 42 months. Sixteen patients (57%) developed neutropenia to < 0.5 x 10(9)/l and 12 (43%) infectious complications. Four patients developed large cell lymphoma (Richter's syndrome) and 2 acute myeloid leukemia. FCM is a useful combination for relapsed or refractory CLL and low grade NHL with high response rates and long duration of response. The role of FCM as first line therapy deserves study as well as its combination with the monoclonal antibody Rituximab.