Oxygen-Reactive Metabolites Are Not Detected at the Effector-Target Interface During Natural Killing

Abstract

Oxygen-reactive metabolites are not detected at the natural killer (NK)-target cell interface in quantities comparable to those seen for other effector-target cell interactions. A novel luminol-coated target cell chemiluminescence assay is described in which luminol is conjugated to the target cell surface with the bifunctional crosslinker 3,3'-dithiobis(propionic acid N-hydroxysuccinimide ester) (DSP). This modification of the basic chemiluminescence assay precludes exclusion of the detection system from the tightly occluded intercellular junction, a possible deficiency in previous investigations. Luminol conjugation does not affect NK-mediated conjugate formation or cytolysis. As NK activity is enriched by a standard series of effector fractionation procedures, chemiluminescence generated against labeled target cells diminishes. Residual chemiluminescence in the most highly NK-active effector fraction is ablated upon antibody and complement depletion of MO2+ cells. This indicates that monocyte contamination is the source of luminol-detectable oxygen-reactive metabolites.

Antibacterial activity of human natural killer cells.

“…The mechanism of NK antibacterial activity appears to be different from mechanisms described for other professional phagocytes . No conclusive evidence has been presented demonstrating oxygen-dependent killing mechanisms in purified NK cells (43) . Moreover, phorbol esters and bacterial products have failed to stimulate chemiluminescence in purified NK cells (D .…”

Role of granule proteins in lymphocyte‐mediated killing

“…Although 0 2 is required for T-cell-mediated killing, reactive oxygen intermediates do not seem to play a direct role in the killing process [22]. Similar results have recently been reported for NK cells [23,24] that also cannot confirm a role for reactive oxygen intermediates in the killing mediated by these cells.…”

Regulation of human B cell activation and antibody production by non‐major histocompatibility complex‐restricted cytotoxic T lymphocytes

“…Activated B cells express the 4F2 molecule which is used by JT9 cells as a target on most cells susceptible to lysis [ll]. On the other hand, the susceptibility of lymphoblastoid cell lines to NK lysis is directly related to their level of expression of 4F2 antigen [18]. One likely hypothesis was that recognition of this structure on activated responding B cells would lead to lysis and explain the inhibitory effect of JT9 cells.…”