In vitro effects of natural killer cells against Paracoccidioides brasiliensis yeast phase

Abstract

Recently, data have been reported suggesting natural killer (NK) cells may function in natural resistance against a fungus, Cryptococcus neoformans. The primary objective of this study was to examine the reactivity of murine splenic cells against another fungus, Paracoccidioides brasiliensis. Levels of NK activity in effector cell pools were varied by: (i) removing nylon wool-adherent cells, (ii) fractionating splenic cells on Percoll discontinuous gradients, (iii) using old and young effector cell donor mice, (iv) using donors from different strains, and (v) pretreating donors with NK-augmenting and-depressing agents. The various effector cell pools were simultaneously used in the 4-h 5tCr release assay with YAC-1 targets to determine the NK reactivity and in the in vitro growth inhibition assay against P. brasiliensis yeast phase targets. In each case, the level of NK reactivity correlated with the ability of the effector cells to inhibit the in vitro growth of P. brasiliensis. NK activity and P. brasiliensis growth-inhibiting ability could be augmented by fractionation of splenic cells through nylon wool or Percoll gradients. The effector cells responsible for the NK activity and P. brasiliensis growth inhibition were characterized as being nylon wool nonadherent, being found in the low-density fractions from Percoll discontinuous gradients, and having no detectable Thy-i antigen or immunoglobulin but having asialo GM1 on their surface. These data support the contention that NK or NK-like cells are responsible for limiting the in vitro growth of P. brasiliensis.

Natural killer cells mediate protection induced by a Salmonella aroA mutant

“…There is evidence for at least four different mechanisms by which NK cells can augment resistance to infection. These include direct killing in vitro of paracocci (14), Cryptococcus species (12), Toxoplasma species (11), Trypanosoma cruzi (10), Salmonella species (8,27), and Eschenichia coli (8) or direct killing in conjunction with antibody by an antibody-dependent cell-mediated cytotoxicity for Salmonella species, meningococci, and Shigella species (23,25,27). NK cells can apparently also lyse mammalian cells harboring bacteria, as has been described for Legionella and Shigella species (3,18,25).…”

“…There are a number of reports in the literature which suggest a role for natural killer (NK) cells in host defense against bacteria (3,8,23,25,38), fungi (12,14,26), and parasites (10,11). We have considered the hypothesis that the vaccine-induced protection against a virulent Salmonella strain at 3 days postvaccination may be mediated by NK cells.…”

Biology of Natural Killer Cells

“…Murine and human NK cells can bind and inhibit growth of fungi such as Cyptococcus neoformans, Paracoccidioides brasiliensis, and Coccidioides immitzi (1044)(1045)(1046). There is some evidence that NK cells play a role in controlling cryptococcal infection.…”

Mapping of the Epitope Recognized by Non‐Specific Cytotoxic Cells: Determination of the Fine Specificity Using Synthetic Peptides

“…Mammalian NK cells have also been shown to bind to and lyse malarial sporozoites [6,7], Toxoplasma [8][9][10], Leishmania [11,12] and trypanosomes [13,14]. Various yeast and fungi [15][16][17][18][19][20][21] interact with NK cells to alter their function either indirectly (lysate blocking of cytotoxicity), or directly by cell contact. The Toxoplasma gondii model [22][23][24] is particularly relevant for studies which indicate a role of NK cells in anti-parasite immunity.…”