The possible association of ecto-5'-nucleotidase (5'-NT) with differentiation of B-cells was explored with the use of normal and neoplastic lymphoblastoid cell lines representing sequential stages of B-cell maturation. There was no relationship between patterns of enzyme expression in the cell lines and immunoglobulin (Ig) secretion, chromosome constitution, proliferative rate, cell volume, or the presence of B1 and B2 antigens. Pre-B-cell lines, which were negative for surface Ig or Ig secretion but positive for cytoplasmic mu-chains, showed the presence of 5'-NT, whereas 9 of 11 lymphoma cell lines, Burkitt's or non-Burkitt's type, both secreting and nonsecreting, did not exhibit enzyme activity. Four myeloma cell lines and 13 of 15 normal B-cell lines were positive for 5'-NT. These results suggested that 5'-NT was present in pre-B-cells and in some very early B-cells. 5'-NT usually disappeared from early and some intermediate B-cells and reappeared in mature B-cells and plasmacytoid cells.

The possible association of ecto-5'-nucleotidase (5'-NT) with differentiation of B-cells was explored with the use of normal and neoplastic lymphoblastoid cell lines representing sequential stages of B-cell maturation. There was no relationship between patterns of enzyme expression in the cell lines and immunoglobulin (Ig) secretion, chromosome constitution, proliferative rate, cell volume, or the presence of B1 and B2 antigens. Pre-B-cell lines, which were negative for surface Ig or Ig secretion but positive for cytoplasmic mu-chains, showed the presence of 5'-NT, whereas 9 of 11 lymphoma cell lines, Burkitt's or non-Burkitt's type, both secreting and nonsecreting, did not exhibit enzyme activity. Four myeloma cell lines and 13 of 15 normal B-cell lines were positive for 5'-NT. These results suggested that 5'-NT was present in pre-B-cells and in some very early B-cells. 5'-NT usually disappeared from early and some intermediate B-cells and reappeared in mature B-cells and plasmacytoid cells.