Bone marrow T cell colony-forming cells: studies of their origin and use in monitoring T cell-depleted bone marrow grafts.
Peripheral blood T cell colony forming cells (T-CFC) are mature T cells. When blood was fractionated into sheep red blood cell receptor positive (E+) and negative (E-) fractions, T cell colony growth was largely restricted to the E+ population. When bone marrow was similarly fractionated, many colonies grew from the E- cells but myeloid colonies also grew making interpretation of colony numbers difficult. We have, therefore, also assessed T cell proliferation during culture as an expansion index (EI) by determining the absolute number of T cells pre and post culture. This data shows that T cell expansion is on average nine times greater in the E- marrow fraction than in the E+ fraction. Studies are presented suggesting that this is because marrow E- cells contain appropriate accessory cells and that high numbers of T cells inhibit T cell growth. The cells giving rise to bone marrow T cell colonies thus appear to be contaminating mature T cells rather than pre-thymic progenitor cells. We have measured T cell expansion in culture as a sensitive assay of T cell contamination following procedures to remove T cells from bone marrow grafts for the prevention of graft versus host disease (GVHD).
D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D002455:Cell Division; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D006086:Graft vs Host Disease / Q000517:prevention & control*; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000166:cytology*