Percentage Of Large Granular Lymphocytes Research Articles

Evaluation of natural killer activity in human schistosomiasis.

Natural killer (NK) activity was assayed in peripheral blood mononuclear cells of patients with schistosomiasis, of patients following treatment, and of uninfected control subjects. The patient populations were from villages in the Qalyub Province, Egypt and around Belo Horizonte , Brazil. NK activity was assayed by the cytotoxicity of 51Cr-labelled K562 target tumor cells. In neither infected population were significant alterations from normal levels found in the percent cytotoxicity per 10(6) cells, or in the lytic units that expressed 25% cytotoxicity. Likewise, prior treatment (2 and 6 months previously) did not alter the group NK activity detected. Similarly, in the Egyptian study there was no difference in the percentage of large granular lymphocytes between the infected and uninfected groups. In parallel studies in Egyptian and Brazilian schistosomiasis patients we did not find any evidence that this chronic infection consistently altered circulating NK activity.

Large granular lymphocytes: morphological and functional properties. I. Results in normals.

Large granular lymphocytes (LGL) represent a morphologically distinct mononuclear cell type. In healthy individuals an average of 12.5 +/- 5.2% of peripheral mononuclear cells exhibit this morphology. Structurally they are characterized by azurophilic granules, light cell density, low surface adherence and expression of Fc-IgG receptors. Functional analyses on LGL suspensions enriched by means of density gradient fractionation and adherence procedures included testing of T-cell and monocyte-specific in vitro reactions as well as evaluation of their natural cytotoxicity (NC). Results indicated a close correlation between the percentages of LGL and the capacity to bind and to lyse NC-susceptible tumor targets. In agreement with others we would thus conclude that LGL embrace the majority of NK-effector cells. The morphological definition of LGL provides an additional tool for the clinical evaluation of this cell mediated immune reactivity.

Rat liver contains a distinct blood-borne population of NK cells resistant to anti-asialo-GM1 antiserum

A high level of anti-tumoral (NK) cytotoxicity was observed in the mononuclear population washed out from the liver microvasculature in rat. The level of cytotoxicity against K562 and YAC1 cells, percentage of large granular lymphocytes (LGL) and of OX8 + cells was significantly higher than in the inflowing portal and also caval blood. A low concentration of adherent, phagocytic and OX6 + (Ia) cells and a higher level of cytotoxicity after removal of adherent cells ruled out the possibility of liver macrophages to be responsible for the cytotoxicity. Surprisingly, the liver-sequestered NK population turned to be resistant to anti-asialo-GM1 antiserum. Thus, liver microvasculature contains a significant number of cells with characteristics of NK cells which constitute a functionally distinct NK population.

Natural killer cell activity in the rat. Analysis of effector cell morphology and effects of interferon on natural killer cell function in the athymic (nude) rat.

Athymic (nude) rats were found to have increased levels of natural killer (NK) activity, 3- to 5-fold higher than in euthymic rats. Studies were performed to determine the nature of the NK cells in these animals and the basis for their increased cytotoxic reactivity. Large granular lymphocytes (LGL), which were previously shown to be the NK cells in euthymic rats, were increased 2- to 7-fold in the peripheral blood and spleen of nude rats. The LGL, enriched by centrifugation on discontinuous Percoll density gradients, were shown to have augmented NK activity similar to that seen with LGL-enriched fractions from euthymic rats. These results indicate that the NK cells in euthymic and athymic rats are morphologically and functionally similar, and that the higher NK activity in nude rats appears to be mainly attributable to an increased proportion of effector cells. In a single-cell cytotoxicity assay, interferon pretreatment of LGL was shown to increase: (a) the percentage of LGL which form conjugates with target cells; (b) the percentage of conjugate-forming cells which kill; and (c) the kinetics of lysis. Different effects were seen depending on the target cell tested.