# MODULATION OF TUMORICIDAL CELLS BY INTESTINAL FLORA

> **NIH NIH R01** · UNIVERSITY OF WISCONSIN-MADISON · 1989 · $140,780

## Abstract

Natural killeer (NK) cells are leukocytes that can kill tumor cells without
having had prior contact with them.  Natural killer cells are considered by
many investigators to be a first line of defense against tumor cells.
Environmental factors that can either enhance or inhibit the tumoricidal
activity of NK cells would obviously play a very important role in the
survival, growth, and metastases of tumor cells.  We recently observed that
the acquisition of an intestinal flora enhances the tumoricidal activity of
splenic NK cells harvested from athymic and euthymic BALB/c mice.  For many
years, epidemiological data has pointed to a connection between the
intestinal flora, diet, and cancer of the breast and colon.  Mucosal
surfaces of the alimentary and genito-urinary tract are in constant contact
with myriad microorganisms.  Many investigators have looked for mutagens,
carcinogens, or cocarcinogens that would be produced by intestinal microbes
in people at high risk for developing breast or colon cancer.  Mutagens and
cocarcinogens, however, appear to be commonplace in the intestinal con of
both high risk and low risk groups.  Our study opens up a new avenue of
research to explain the association between diet, intestinal flora, and
cancer by exploring the effect of intestinal bacteria on the tumoricidal
activity of NK cells in the spleen and especially the intestinal lamina
propria of mucosal surfaces which are in constant contact with viable
microbes.  The mucosal microflora, depending on it's composition, can exert
either an enhancing or a suppressive effect on the tumoricidal activity of
NK cells in the spleen and the lamina propria.  It is worth pointing out
that prior to our studies several reports stated that the microbial flora
did not have an effect on NK cell activity.  Our work shows that the
intestinal flora can have a pronounced and long-terrm affect on the
tumoricidal activity of NK cells.  We want to expand our original
observation and carry out studies to learn more about the this important
association between intestinal flora and the tumoricidal activity of NK
cells.  Our results will be very pertinent to the etiology of cancers that
develop in or on any mucosal tissue that is in constant or intermittent
contact with a microbial flora.

## Key facts

- **NIH application ID:** 3174263
- **Project number:** 5R01CA036695-03
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **SAM.gov UEI:** LCLSJAGTNZQ7
- **Principal Investigator:** EDWARD BALISH
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1989
- **Award amount:** $140,780
- **Award type:** 5
- **Project period:** 1987-01-01 → 1990-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3174263

## Citation

> US National Institutes of Health, RePORTER application 3174263, MODULATION OF TUMORICIDAL CELLS BY INTESTINAL FLORA (5R01CA036695-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3174263. Licensed CC0.

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