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The metabolism of recombinant human erythropoietin (rHuEpo) labelled with 125I has been investigated in five normal and nine 5/6-nephrectomised rabbits. The plasma erythropoietin half-life was significantly prolonged at 5.1 +/- 1.2 h (mean +/- SD) in the 5/6-nephrectomised rabbits, compared to 3.0 +/- 0.4 h in sham-operated controls (P less than 0.001). The disappearance of 125I-labelled rHuEpo is biphasic. Examination of serum by fast protein liquid chromatography (FPLC) following administration of 125I-labelled rHuEpo by FPLC showed a single peak of radioactivity in all rabbits except two of the nephrectomised group. In serum from both of these animals a second labelled peak was found, corresponding to material of MW 200,000-250,000 D. We conclude that the 5/6-nephrectomised rabbit provides a stable model for the study of hormonal metabolism in chronic renal failure.

Erythropoiesis has been examined in relation to kidney function in 38 patients during the 3-month period following successful renal transplantation, using serial determinations of erythropoietin, haemoglobin, and creatinine. Two peaks of serum erythropoietin were observed: an early peak that occurred within 2 days of transplantation and was observed in ten patients, and a late one between 8 and 30 days, observed in 28 patients. The early peak did not produce an increase in haemoglobin and occurred only in the presence of delayed onset of graft excretory function when serum creatinine was greater than 1000 mumols/l. The ineffectiveness of the early peak may be due to the uraemic environment, which is probably a sequel of the tubular damage associated with postoperative acute tubular necrosis. The late peak followed a decrease in serum creatinine to less than 200 mumols/l and was associated with an increase in haemoglobin of 3-4 g/dl during the next 2-6 weeks.

Dipeptidylaminopeptidase IV (DAP IV) cytochemical reactivity was investigated in monoclonal antibody defined T-lymphocyte subpopulations from normal blood and in cells from a series of T-cell leukemias of defined immunologic phenotype. A combined monoclonal antibody/immunocolloidal gold technic, which enabled simultaneous visualisation of immunogold label and DAP IV reactivity, was used to study enzyme reactivity in normal T-cell subpopulations. Single or several discrete granules of DAP IV reaction product were observed in 72% of OKT3+ and OKT4+ cells, whereas a significantly (P less than 0.01) lower percentage of OKT8+ cells (41%) displayed positivity; B-cells were invariably DAP IV negative. In the T-cell leukemias, DAP IV reactivity was strongest in T-lymphoblastic lymphoma and T-prolymphocytic leukemia cells. In contrast, DAP IV activity was absent or expressed in a minority of cells of the more immature T-acute lymphoblastic leukemia. The enzyme reaction also was negative in lymphocytes from other mature T-cell leukemias: T-chronic lymphocytic leukemia (OKT8+), adult T-cell lymphoma-leukemia, and Sezary syndrome (both OKT4+). DAP IV expression did not parallel that of acid phosphatase or alpha-naphthyl acetate esterase in leukemic T-lymphoid cells except in T-lymphoblastic lymphoma and T-prolymphocytic leukemia, where a strong reaction with the three hydrolytic enzymes was observed.

In Northern Ireland, with a population of 1.5 million, thirteen cases of Letterer-Siwe disease have been diagnosed over the past 21 years. The average age of onset was 10.5 months. There was a 69% mortality with an average survival time from diagnosis to death of 3.3 months. Four children survived with no morbidity. All deaths were from pulmonary complications, but two cases with pulmonary infiltration responded to treatment with quadruple chemotherapy. There were no familial cases in this study.

A 13-year-old female was on maintenance therapy for acute lymphoblastic leukemia. On three occasions she received methotrexate orally and each time this was associated with reactivation of scabies rash. The mechanisms for this phenomenon are discussed.