The heterogeneous distribution of 5'-nucleotidase among rabbit lymphocytes
Gregory, S.H.; Kern, M.
Journal of Immunology 123(3): 1078-1082
1979
ISSN/ISBN: 0022-1767 PMID: 224108 Document Number: 151282
Assay of 5'-nucleotidase activity revealed non-uniform enzyme activity distribution among rabbit lymphoid tissues. Although 5'-nucleotidase activity was readily observed in rabbit spleen cells, it was essentially undetectable in cells derived from thymus, blood, bone marrow and appendix. Popliteal lymph node cells exhibited approximately 6% of the specific activity observed in spleen. Cytochemical reactions carried out on splenocyte smears showed that only 20% of spleen cells in the total population possessed demonstrable 5'-nucleotidase activity. The activity bulk was not principally associated with T [thymus-derived] cells, B [bone marrow-derived] cells or macrophages. Association of some enzyme activity with subpopulations of these cell types could not be excluded by this kind of analysis. Autoradiographic studies indicated that 5'-nucleotidase did not afford selective advantage to those splenocytes possessing the enzyme; enzyme-bearing and enzyme-nonbearing cells, when present in the same population, readily incorporated label derived from extracellular [3H]adenosine-labeled 5'-AMP. Thymus cells which did not contain a 5'-nucleotidase-bearing population were unable to utilize extracellular 5'-AMP. Distribution of 2 other plasma membrane-associated enzymes was explored. Whereas nucleotide pyrophosphatase was more uniformly distributed, the phosphodiesterase I distribution was quite heterogeneous yet distinguishable from that observed for 5'-nucleotidase.