Jeanne M. Connolly

A method for the specific histochemical demonstration of antibody in cells and parts of cells is described. It consists of carrying out a two stage immunological reaction on frozen sections of tissues: (a) allowing reaction between antibody in the tissue and dilute antigen applied in vitro, and (b) the detection of those areas where this antigen has been specifically absorbed by means of a precipitin reaction carried out with fluorescein-labelled antibody. Examination under the fluorescence microscope reveals the yellow-green fluorescence of fluorescein over those areas where a precipitate has formed. A study of the hyperimmune rabbit on the first few days after the last of a series of intravenous antigen injections reveals that antibody against human gamma-globulin or ovalbumin is present in groups of plasma cells in the red pulp of the spleen, the medullary areas of lymph nodes, the submucosa of the ileum, and the portal connective tissue of the liver. Because of extensive non-specific reactions, the bone marrow could not be examined. Small amounts of antibody were occasionally visible in cells in the lymphoid follicles of the spleen and lymph nodes, so that a minor contribution by lymphocytes to antibody synthesis cannot be excluded.

BACKGROUND: Diets rich in omega-6 polyunsaturated fatty acids (e.g., corn oil and other fats containing linoleic acid) stimulate the growth and metastasis of human breast cancer cells in athymic nude mice. On the other hand, diets containing fish oil, which is rich in omega-3 fatty acids (e.g., eicosapentaenoic and docosahexaenoic acids), exert suppressive effects. PURPOSE: Our objective was twofold: 1) to compare the effects of diets containing linoleic acid with those of diets containing eicosapentaenoic acid and docosahexaenoic acid on the growth and metastasis of MDA-MB-435 human breast cancer cells in the nude mouse model and 2) to determine how such effects relate to observed changes in the chemical content of tumor fatty acids and eicosanoid production. METHODS: Groups of 30 female athymic nude mice were fed 20% (wt/wt) fat diets containing either linoleic acid (8%) alone, linoleic acid (8%) plus eicosapentaenoic acid (4%) or docosahexaenoic acid (4%), or linoleic acid (4%) plus eicosapentaenoic acid (8%) or docosahexaenoic acid (8%) for 7 days before one million MDA-MB-435 cells were injected into a thoracic mammary fat pad. Diets were continued for 12 more weeks. Primary tumors were measured weekly. The mice were then killed and necropsied, and tumor tissues preserved. Cell membrane phospholipid fatty acid analyses and eicosanoid assays were performed. All P values represent two-tailed tests of statistical significance. RESULTS: The growth of the primary tumors was retarded in mice fed the diets supplemented with eicosapentaenoic or docosahexaenoic acid compared with the growth of primary tumors in mice fed the 8% linoleic acid diet. Growth inhibition was statistically significant (P < .05) and most effective in association with the diets containing 8% of either omega-3 fatty acid, where tumors were smaller than those in the group fed the diet containing 8% linoleic acid alone at all time points after the 2nd week. The occurrence and severity of lung metastases were reduced in the groups fed omega-3 fatty acid (P < .05). In groups of mice fed eicosapentaenoic or docosahexaenoic acid, the representation of these acids in tumor phospholipids increased, with a statistically significant reduction in the concentrations of arachidonic acid (all groups), tumor 12- and 15-hydroxyeicosatetraenoic acid, and prostaglandin E. Levels of 5-hydroxyeicosatetraenoic acid and leukotriene B4 were unaffected by the omega-3 fatty acids. CONCLUSION: The inhibitory effects of dietary fish oil on human breast cancer cell growth and metastasis in this model system are ascribable to its high eicosapentaenoic acid and docosahexaenoic acid content; the mechanism very likely involves suppression of tumor eicosanoid biosynthesis. IMPLICATION: Future dietary intervention trials designed to reduce the risk of recurrence in the postsurgical breast cancer patient should include the evaluation of eicosapentaenoic acid and docosahexaenoic acid supplementation.

After an antigenic stimulus, antibody is first demonstrable in the cytoplasm, and often in a spot in the nucleus, of large, immature cells in the medullary areas of the lymph node draining the site of injection. Morphologically, these cells have basophilic cytoplasm and a large nucleus, and are typical hematogenous stem cells. As these cells multiply and differentiate, the concentration of antibody in their cytoplasm increases, until colonies of typical mature plasma cells containing antibody have developed. There is a marked difference between the primary and the secondary responses, the former characterized by the development of very few antibody-containing cells while in the latter there are hundreds in a similar area. The morphology of the cells involved in both responses is identical. Occasionally, antibody was also found in low concentration in association with the lymphoid follicles. The implications of these findings for an understanding of antibody synthesis are discussed.

Dietary lipids may influence breast cancer progression and prognosis. The MDA-MB-231 human breast cancer cell line was used to examine the direct effects of the various classes of free fatty acids (FAs) on growth in serum-free medium and the involvement of eicosanoid biosynthesis. Linoleic acid, an omega 6 FA, stimulated MDA-MB-231 cell growth with an optimal effect at a concentration of 0.75 microgram/ml, whereas oleic acid, an omega 9 FA, produced growth stimulation at 0.25 microgram/ml but was inhibitory at higher concentrations. Docosahexaenoic acid exhibited a dose-related inhibition of cell growth at concentrations ranging from 0.5 to 2.5 micrograms/ml; eicosapentaenoic acid, also an omega 3 FA, was less effective. Similar inhibitory effects occurred with saturated FAs. Indomethacin, which at high concentrations is an inhibitor of both the cyclooxygenase- and lipoxygenase-catalyzed pathways of eicosanoid synthesis, suppressed cell growth stimulation by an otherwise optimal dose of linoleic acid when present at 40 micrograms/ml. Experiments with piroxicam, nordihydroguaiaretic acid, and esculetin, other inhibitors of eicosanoid biosynthesis with varying selectivity for enzymes of the prostaglandin and leukotriene pathways, indicated that MDA-MB-231 cell growth was dependent on leukotriene rather than prostaglandin production.