The back-bone of the human immune system.

The following links provide information on research related to natural killer cells - one of the main types of white blood cells which work as part of the human immune system.   Natural killer cells are being found to play a primary role in preventing and removing cancer cells in the body, removing many types of viruses (including herpes and measles) and have been found low in women with endometriosis. Of great concern is the fact that many common chemical sources are being found to damage, weaken and lower natural killer cell function and numbers. We have located medical journal articles on natural killer cell function and have summarized these for you below.
Thank you - CHEM-TOX.COM

Natural Killer Cells in Human Cancer

Source: Biochimica et Biophysica Acta, 865: 329-240, 1986

The journal article summarizes various research regarding what is currently known about natural killer cell function and then describes their important role in cancer prevention and cancer removal.  Written by the Department of Immunology, Smith Kline & French Laboratories, Philadelphia, PA, this information should be of special interest to parents of children with brain cancer, neuroblastoma and leukemia as these cancers have been found to be associated with defective natural killer cell function.  The following are direct quotes regarding major points from the article.

  • "Moreover, the efficacy of the different host defense mechanisms in destroying malignant cells may depend upon the extent of tumor burden, immunogenicity and site of tumor growth.  For example, certain immune and nonimmune mechanisms may prove effective in destroying circulating tumor cells even though they might exert only a limited effect against the extravascular primary neoplasm.  This may be attributed to the observation that unlike the cells within a solid tumor, tumor cells enter the circulation as single cells or small clumps and are, therefore, highly accessible and more vulnerable to destruction by immune and non-immune defense mechanisms."  pg. 214

  • "Indeed, most tumor cells that enter the circulation are destroyed during the first 24 h and only a few cells succeed to extravasate and develop into metastatic foci in the organ parenchyma."   pg. 214

  • Also, the incidence of spontaneous malignant lymphomas was reported to be increased in NK-deficient mice carrying the beige mutation.  In contrast, the relatively low incidence of tumor development in athymic nude mice that exhibit high NK cell-mediated cytotoxicity suggested that a T cell-independent mechanism may be operative in immunosurveillance."  pg. 214

  • Virtually  all NK cell activity in humans is  mediated by large granular lymphocytes (LGL) which represent 5-10% of peripheral blood mononuclear cells." pg. 215

  • NK cells express receptors to IL-2 (interleukin 2) and can  proliferate in response to T cell mitogens and IL-2."  pg. 215

  • NK cells originate in the bone marrow and exhibit a characteristic organ distribution, their activity being highest in peripheral blood and then, in descending order, spleen, lymph nodes and bone marrow, and absent in the thymus." pg. 215

  • ...NK cells and/or their precursors are highly sensitive to treatment in vivo with cyclophosphamide, B-estradiol and Sr.  Animals treated with such agents and the beige mouse exhibit low levels of NK cell activity and provide valuable models for studying the in vivo (animal) role of NK cells in host defense against neoplasms."  pg. 215

  • Also, depletion of NK cells in vivo by treatment with antiasialo-GM1 antibodies (antibodies injected to remove natural killer cells) resulted in increased tumorogenicity and percent takes of NK sensitive tumor cells transplanted into syngeneic and nude mice."  pg. 216

  • Also, it should be emphasized that NK-mediated resistance against  tumor growth in vivo was expressed only when a small number of tumor cells were inoculated.  Therefore, it was concluded that NK cells serve as a rapidly acting first-line defense mechanism that is involved in the early destructive events following tumor implantation."   pg. 216

    CHEM-TOX COMMENT:   This last statement provides a biological explanation why cancers would develop more rapidly in children living in proximity to chemical sources which can suppress natural killer cell function (i.e. agriculture areas, home pesticide & chemical use, etc.)

  • Activation of NK cells may be easily achieved by treatment with interferon, interferon inducers, interleukin-2 and bacterial adjuvants."  pg. 219

  • During surgical manipulation of the primary  tumor, potential malignant cells may be released into the circulation and develop into secondary metastatic foci. "  pg. 224

  • Moreover, the suppressive effects of surgery and anesthesia on NK cell activity may further facilitate the survival of tumor cells released from the primary or metastatic tumor growth and contribute to the increased incidence of metastasis.  Therefore, certain BRM, including low doses of interferon, may prove safe and, if appropriate applied, effective in preventing further tumor dissemination and metastasis."  pg. 226

CHEM-TOX COMMENT:   Exposure to anesthethesia compounds have been found to weaken immune system function which also explains the high incidence of infection following anesthesia exposure.

Department of Tumor Biology, Karolinska Institutet
S-104 01 Stockholm, Sweden