The pit cell: Description of a new type of cell occurring in rat liver sinusoids and peripheral blood

Abstract

Pit cells--a new type of cell first described here and so named because they contain highly characteristic granules--are situated in the wall of rat liver sinusoids, and have hyaloplasmic pseudopodia intermingling with the microvilli of the parenchymal cells. The characteristic granules are mainly situated at one side of the nucleus, the other side showing organelle-free hyaloplasm. Pit cells are also found in portal tracts and in granuloma-like cellular aggregates. They also occur in rat peripheral blood, although there are morphological differences between cells in these two sites. Pit cells can be regarded as regular inhabitants of the sinusoidal wall, and therefore belong to the series of sinusoidal cells, i.e., the endothelial (Wisse, 1972), Kupffer (Widmann et al., 1972; Wisse and Daems, 1970; Wisse, 1974a, b), and fat-storing cells (Ito, 1973). Pit cells do not phagocytose and do not react to a great number of experimental conditions, to which endothelial and Kupffer cells do react (Wisse, 1972, 1974b). Mitosis has been observed in a pit cell. The function of pit cells remains obscure, but an endocrine function is suggested by the morphology of their highly characteristic granules.

Pit cells (hepatic natural killer cells) of the rat induce apoptosis in colon carcinoma cells by the perforin/granzyme pathway

“…1 Pit cells, together with Kupffer cells, represent the first line of cellular defense against invading cancer cells in the liver. Pit cells were first described in 1976 by Wisse et al, 2 and their function as natural killer (NK) cells was suggested by Kaneda et al 3 They were first isolated by Bouwens et al, and their NK cell nature was ascertained. 4 Cytotoxicity experiments, using the 51 Cr release assay, against various tumor cell lines showed that pit cells are the most cytotoxic cells of the naturally occurring NK cells; their level of cytotoxicity is comparable with lymphokine-activated killer cells.…”

The role of adhesion molecules in the recruitment of hepatic natural killer cells (pit cells) in rat liver

“…Pit cells are a unique population of cells occurring in rat buffered saline (PBS) supplemented with 0.1% ethylenediaminetetliver sinusoids, 1 and can be considered as natural killer (NK) raacetic acid, at a pressure of 50 cm H 2 O, and the perfusate was cells 2,3 with large granular lymphocyte (LGL) morphology. 4 collected through cannulation of the inferior vena cava.…”

Interleukin 4 inhibits the production of some acute‐phase proteins by human hepatocytes in primary culture

“…The data collected on the IL4 function raise the possibility that this cytokine (1) could be produced by liver-associated lymphocytes including large granular (i.e. Pit cells) and agranular lymphocytes [37,38], since these cells display natural killer and lymphokine-activated killer activities [38]; (2) could act on other hepatic functions (including plasma proteins and cytochrome P450 enzymes) and may antagonize and/or cooperate with other cytokines; (3) could be involved in the development of some liver diseases. Indeed, Schlaak et al [39] have recently reported elevated IL4 production by liver infiltrating T cells in autoimmune hepatitis.…”