The proto-oncogene, c-kit, encodes a transmembrane tyrosine kinase receptor (KIT) and plays an important role in haemopoiesis. We have identified a 95 kD soluble form of KIT (S-KIT) in culture supernatant of human megakaryoblastic cell line, CMK. To study the physiological significance of S-KIT, we have established a sensitive sandwich ELISA system. Serum samples from healthy individuals contained detectable amounts of S-KIT. Next, we determined a total of 220 samples from 134 patients with haemopoietic disorders. A considerable number of patients with acute myeloid leukaemia (AML), especially those with more immature phenotypes (M0, M1 or M2) had elevated levels of serum S-KIT. Those levels decreased to the normal range after effective chemotherapy. In chronic myeloid leukaemia, patients with myeloid blastic crisis showed markedly elevated levels of serum S-KIT. In contrast, S-KIT levels decreased in cases with either acute or chronic lymphoid leukaemia. There was a tendency for patients with severe aplastic anaemia to show decreased levels, but it was not significant. In myelodysplastic syndrome, S-KIT levels appeared to vary by subsets, with higher concentration in more advanced forms of the disease. Although the functional role of S-KIT is not yet elucidated, these results suggest that the serum S-KIT levels may reflect the pathological states of various haematological disorders.

A 72-year-old Japanese woman suffered from mild pancytopenia 3 years before her initial hospitalization. On admission, the levels of trace elements, particularly copper, and ceruloplasmin were significantly decreased in her blood serum. Abdominal lymphadenopathy and bone marrow dysplasia were detected. Hemosiderin deposition was observed in her lymph nodes and bone marrow, and magnetic resonance imaging suggested its deposition in various organs. A novel missense pathogenic variant (c.T1670G) was detected in the ceruloplasmin gene, resulting in an amino acid change (p.M557R). When copper deficiency is accompanied by cytopenia and dysplasia in a patient, it is worthwhile to consider a differential diagnosis of aceruloplasminemia.

We present a case of granular lymphocytic leukemia (GLL) associated with pure red cell aplasia (PRCA). Twenty-seven percent of the peripheral blood mononuclear cells (PBMC) were positive for TCRδ1 but not for δTCS1 (Vδ2), and a rearrangement of the TCR chain (Jδ1) gene was detected. The PBMC and serum from the patient slightly suppressed CFU-E but not BFU-E colony formation in vitro. These findings suggest that monoclonal proliferation of TCRγδ-positive granular lymphocytes (GL) can be associated with PRCA even in a patient having a small proportion of leukemia GL, which we propose to designate as ‘smoldering GLL’.

Hairy cell leukemia (HCL) is occasionally misdiagnosed as aplastic anemia when only a few leukemic cells are present in the circulation. Here, we describe a patient with HCL who initially presented with pancytopenia and received a diagnosis of aplastic anemia. The patient was treated with immunosuppressive therapy including cyclosporine A and anti-thymocyte globulin (ATG). No blood cell transfusion was required for approximately 3 years after ATG therapy. She was referred to our hospital because of an abdominal mass and requiring periodic blood transfusions. A bone marrow biopsy at this time revealed proliferation of lymphocytes with a fried egg appearance and an increase in reticulin fibers that are typical findings of HCL. It is notable that our patient with a presumably long history of HCL and an increase in marrow reticulin fibers showed good recovery of hematopoiesis after cladribine therapy. Some HCL patients may receive an initial diagnosis of aplastic anemia and may show a good response to ATG masking the underlying HCL.

Pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) potently stimulates platelet production in humans, mitigates thrombocytopenia associated with nonmyeloablative chemotherapy, and reduces the need for platelet transfusions. Its long-term effect in patients, however, is not well understood. We report a patient with aplastic anaemia who received 3 cycles of PEG-rHuMGDF 3 times a week for up to 2 years. Platelet counts slightly increased 1 week after the initiation of PEG-rHuMGDF therapy, bleeding episodes decreased, and there was no need for platelet transfusion. Administration of PEG-rHuMGDF increased not only platelet numbers but also reticulocyte counts, and reduced the need for erythrocyte transfusions as well. There were no significant adverse events, and no neutralizing antibodies were detected in the patient.