SUMMARYA cloning technique was used lo estimate (he frequency of proliferating Tcell precursors, the growth capacity of clone-forming cells and the functional activity of clones established in vitro from peripheral blood lymphocytes of young and old people. The mean frequency of proliferating precursors was lower in the elderly as was the proliferative capacity of CD8^ clones. In contrast, CD4 * and CDl 6 *" clones showed a proliferation similar to that obtained from young subjects. When the clones were examined for their functional activity, CD4 ' clones from both groups failed to show any cytolylic activity, while CDS ' clones exerted cytolysis against K562 and in antibody-dependent cell-mediated cytotoxicity but this function was reduced in clones derived from old subjects. Similarly, CDIG"^ clones from the elderly showed a decreased activity at some effcctor-to-target cell ratios. We conclude that the impaired functional activity (T or NK-dcpendent) found in the peripheral blood of aged subjects persists after in vitro selection when these cells are analysed at clonal level.

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The aim of this study was to test different metals, widely employed in constructing prosthetic devices, by in vitro methods. Biological effects of such materials were analyzed through four different assays on human lymphocytes and granulocytes. The lymphocyte proliferation assay gave quantitative results, while the viability test showed the morphological appearance of the cells correlated well with previous results. NK cytotoxicity and granulocyte chemokinesis tests provided interesting data on leucocyte performance when challenged with metals. Therefore the present study adds new basic information on cell behaviour when metal products are present in the body, e.g. around devices implanted in human tissues.