Hiroshi Kodaira

Eosinophilia associated with proliferation of CD3+4−8− αβ+ T cells with chromosome 16 anomalies

We describe a patient with eosinophilia and an abnormal CD3+4−8−αβ+ T‐cell population. Chromosomal analysis of sorted CD3+4−8− cells revealed abnormal karyotypes on chromosome 16. In the presence of IL‐2 the production of IL‐5 from CD3+4−8− cells was higher than that from CD3+4+/8+ cells. Eosinophil survival‐enhancing activity in the patient serum was inhibited by a combination of anti‐IL‐5 and anti‐GM‐CSF monoclonal antibodies. These data suggest that increased production of IL‐5 and GM‐CSF from the abnormal CD3+4−8− cells might cause eosinophilia.

A selective amplifier gene for tamoxifen‐inducible expansion of hematopoietic cells

We have developed a novel system for expansion of gene‐modified hematopoietic stem/progenitor cells to overcome the low efficiency of current gene transfer methodology. This system involves ‘selective amplifier genes’, that encode fusion proteins between the granulocyte colony‐stimulating factor receptor (GCR) and the hormone‐binding domain of estrogen receptor (ER). Hematopoietic progenitors expressing the chimeras showed estrogen‐responsive growth in a controllable manner. However, endogenous estrogen may activate the fusion proteins in vivo, depending on the hormonal status of the subjects.

Fas and Mutant Estrogen Receptor Chimeric Gene: A Novel Suicide Vector for Tamoxifen-inducible Apoptosis

Several cancer gene therapy strategies involve suicide genes to kill the neoplasm, or to regulate effector cells such as lymphocytes. We have developed an inducible apoptosis system with a Fasestrogen receptor fusion protein (MfasER) for rapid elimination of transduced cells. In the present study, we further improved this molecular switch for estrogen‐inducible apoptosis to overcome concerns with the wild‐type estrogen receptor and its natural ligand, 17β‐estradiol (E2). The ligand‐binding domain of MfasER was replaced with that of a mutant estrogen receptor which is unable to bind estrogen yet retains affinity for a synthetic ligand, 4‐hydroxytamoxifen (Tm). The resultant fusion protein (MfasTmR) and MfasER were expressed in L929 cells for examination of their ligand specificities. Tm induced apoptosis in MfasTmR‐expressing cells (L929MfasTmR) at 10‐8M or higher concentrations, but induced no apoptosis in MfasER‐expressing cells (L929MfasER) at up to 10‐6M. On the other hand, E2 induced apoptosis in L929MfasER at concentrations as low as 10‐10–10‐9M, while it did so partially in L929MfasTmR at concentrations greater than 10‐7M. Thus, L929MfasTmR cells were highly susceptible to Tm, but refractory to E2, with 100–1,000 times more tolerance than L929MfasER. These results suggest that the MfasTmR/Tm system would induce apoptosis in the target cells more safely in vivo, working independently of endogenous estrogen.

Resistance to activated protein C and Arg 506 Gln factor V mutation are uncommon in eastern Asian populations

We investigated the prevalence of the factor V (FV) Arg 506 Gln mutation in healthy subjects from three eastern Asian countries (Japan, n = 270; China, n = 113; and Korea, n = 93) and in 26 Japanese patients showing venous thromboembolic events. The patients were also examined for activated protein C (APC) resistance by using the Coatest APC resistance kit. The FV mutation was investigated by polymerase chain reaction and restricted enzyme digestion with MnlI RFLP assay of the FV gene. None of the patients showed APC resistance, while all subjects examined were homozygous for Arg at position 506 of the FV gene. Our results imply that FV mutation and APC resistance contribute little to venous thrombotic diseases in eastern Asia.