| Abstract: | Subpopulations of human lymphoid cells are capable of spontaneously fusing with fibroblasts of human or murine origin to form human-human or human-mouse hybrid cells. These cells were present in thymus, spleen, and bone marrow. After fractionation on discontinuous bovine serum albumin gradients, the cells were found in the less dense layers of the gradient. Cells of fetal origin, except for bone marrow, fused spontaneously at a higher rate than those of adult origin. The highest rate of fusion was found with adult bone marrow cells. These lymphoid cells appear to be “thymus-derived” cells. |
