E rosette‐positive agar colonies containing the Philadelphia chromosome in chronic myeloid leukaemia

Abstract

In an attempt to document possible T‐cell involvement in chronic myeloid leukaemia, E rosette‐positive colonies (ERPC) were grown in agar culture using a T‐cell‐conditioned medium. Colonies were grown from whole mononuclear cells (WMN), nonadherent E rosette‐positive (NAT +) and nonadherent E rosette‐negative (NAT‐) cells. Cells collected from the colonies after 10 d in culture were 99–100% E rosette‐positive. 8 metaphases were obtained from both NAT+ and NAT‐ ERPCs. In NAT‐ ERPCs, 5 out of 8 metaphases were positive for the Philadelphia (Ph1) chromosome as compared to 1 Ph1 positive out of 8 metaphases in the NAT + ERPCs. These results suggest that, at least in this particular patient we studied, a subpopulation of E rosette‐positive cells derived from the NAT‐ cell fraction express the Ph1 chromosome.