[Large, granular lymphocytes, a new population of mononuclear blood cells]

Large granular lymphocytes (LGL) represent a morphologically distinct and new population of mononuclear blood cells. In normals on average 12% of their peripheral blood mononuclear cells exhibit morphological features of LGL. In this article we summarize experimental evidence suggesting that LGL represent the effectors of spontaneous cell mediated cytotoxicity responses in normal as well as in diseased states. This conclusion is based on two main findings: 1. the frequency of LGL correlates with the capacity to mediated spontaneous cell mediated cytotoxicity when pooled data of normal controls were analyzed, as well as when different density fractions or organs from one and the same individual were compared. 2. disease associated reduction in the numbers of LGL is invariably accompanied by an impaired spontaneous cytotoxicity. It thus appears that evaluation of LGL by morphological means represents a new way to assess spontaneous cell mediated cytotoxicity responses.