Research into the effects which normal or immunologically abnormal thymic epithelial cells or epithelial cells of thymoma exert on Blood Stem Cells

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We made primary culture of thymic tissue obtained from thoracic surgical operation cases. Donors of thymic tissue were classified into four groups. First group is from fetal period to less than 2 year old, second one is from 2 to less than 10, third one is from 10 to less than 20, fourth one is 20 or more.At primary culture, thymic epithelial cells continued to proliferate until end of second week in 1st or 2nd group but in 3rd or 4th group cells barely proliferated after 1 week.Cultured thymic epithelial cells were categorized into three types with shape of cells at primary culture. Type 1 had small cell body and gathered each other. Type 2 had wide body and scattered on the bottom of culture bottle. Type 3 had wide body and gathered each other. Type 1 cells expressed keratin brightly but type 3 cells dully. In type 2 cells, some cells expressed keratin and the others expressed vimentin.We made secondary culture of thymic epithelial cells. At first thymic epithelial cells decreased remarkably in all groups. In 1st or 2nd group, cells started to proliferate at 2nd day of culture but in 3rd or 4th group, cells started to proliferate only a little at 4th day of secondary culture.Mononuclear cells were obtained from bone marrow of ribs at various surgical cases, which were removed cells that expressed CD3 or CD4 or CD8 brightly. Supernatant of thymic epithelial cell culture of each group was added to the CD3-4-8 cell fraction and after 4 days incubation, expression of CD3 or CD4 or CD8 were detected by FACScan. In lymphoid lineage 4th group s ratio was decreased compared with control or 1st or 2nd or 3rd group. In granulocyte lineage 4th one s ratio decreased compared with control. In blast lineage no remarkable change was detected.We analyzed the effects of supernatant of thymic epithelial cell culture. In 1st or 2nd group CD3+4-8- subset and CD3+4+8- subset increased compared with control. In 3rd or 4th group CD3+4+8- subset had no change compared with control.