OxyFile #163

Induction of Interferon-y Production by Human Natural Killer Cells 
Stimulated by Hydrogen Peroxide

Journal of Immunology, Vol. 134, No. 4, April 1985

Tetsuo MUNAKATA., Umeko SEMBA., Yoko SHIBUYA. Koichi KUWANO. Masanobu 


Interferon (IFN)-inducing activity of hydrogen peroxide in human 
peripheral mononuclear cells was investigated. Among the mononuclear 
cells, purified nonadherent cells produced IFN, but not B cells and 
monocytes. The maximal titer of IFN by purified nonadherent cells was 
observed after a 72-hr cultivation in the presence of 10(-2) mM H2O2 
without affecting their viability. Furthermore, the purified 
nonadherent cells, but not the unpurified mononuclear cells, showed an 
augmented cytotoxicity to K562 when stimulated with hydrogen peroxide.

By using Percoll discontinuous density gradient centrifugation, 
peripheral blood nonphagocytic and nonadherent mononuclear cells were 
divided into the low and high density fractions for which natural 
killer (NK) cells and T cells were enriched, respectively. The NK-
enriched low density fractions, but not the T cell-enriched high 
density fractions, showed IFN production by the stimulation of 
hydrogen peroxide. IFN production as well as large granular 
lymphocytes and HNK-1+. Leu-ll+ cells of the NR-enriched fractions 
were abrogated by treatment of the cells with monoclonal antibody 
against human NK cells (HNK-1+) but not against T cells (OKT3) in the 
presence of complement. Moreover, hydrogen peroxide-inducing IFN 
production seems to be regulated by monocytes. The antiserum 
neutralizing IFN-a and IFN-B failed to neutralize substantially IFN-
produced NK cells. The treatment with either pH 2 or antiserum-
neutralizing human IFN-y resulted in marked reduction, indicating that 
a major part of IFN was IFN-y. The purified nonadherent cells showed 
IFN production and augmented cytotoxicity when cultured separately 
from activated macrophages by opsonized zymosan; furthermore, both IFN 
production and enhancement of cytotoxicity were abrogated by catalase.

These results suggest that both exogenous and endogenous hydrogen 
peroxide might be responsible for a part of immunoregulation.

Received for publication August 9, 1984
Accepted for publication November 27, 1984