**8.2 Immunomodulatory activity**

The areca nut extract was found to increase the white blood cell count postchallenge with *Staphylococcus aureus* induction significantly indicating that the extract could stimulate the hemopoietic system. Another study found that areca nut extract can induce calcium signals in at least three immune cell lines and human primary immune cells (PBMCs), inducing the production of pro-inflammatory cytokines. Further separation of the PBMCs into T cells, B cells, and monocytes would potentially be of interest in elucidating specific responses to each cell subtype [70]. However, areca nut extract can also induce antigen-specific immune responses and promote inflammatory reactions *in vivo*, which may contribute to immune deregulation associated with areca-related diseases [71]. In fact, the study of areca nut as an immunomodulatory drug still causes various results. It depends on the content of polyphenolic compound in the areca nut extract which greatly affects the efficacy of the nut.

The areca nut can also increase the activity and capacity of macrophages. The process by which a cell ingests and disposes of foreign material, including microorganisms is called phagocytosis. In normal conditions, most phagocytes are circulating in the blood and when there is an inflammation, the phagocytes will leave the bloodstream and migrate to the site of inflammation. The circulation in the capillaries and venules is rapidly moving with the red blood cells in the mainstream and neutrophils and other leukocytes tending to flow more slowly along the vessel's periphery. Monocytes and macrophages have the same functions as neutrophils but for a longer time and in a later stage of the inflammatory response. Monocytes are produced in the bone marrow, enter the circulation, and migrate to the

*Antioxidant Activity of Areca Nut to Human Health: Effect on Oral Cancer Cell Lines… DOI: http://dx.doi.org/10.5772/intechopen.96036*

inflammatory site, where they develop into macrophages. Macrophages are more active as phagocytes than their monocytic precursors. Macrophages, particularly those residing in the tissue, are often important cellular initiators of the inflammatory response.

Several bacteria are resistant to killing by granulocytes and can even survive inside macrophages. Microorganisms such as *Mycobacterium tuberculosis*, *Salmonella typhi,* and *Mycobacterium leprae* can remain dormant or even multiply inside the phagolysosomes of macrophages. However, the bactericidal activity of macrophages can be markedly increased with the help of inflammatory cytokines produced by cells of the acquired immune system (a subset of T lymphocyte) or cells activated through Toll-like receptors. Macrophage activation results in increased phagocytic activity, the size of itself, plasma membrane area, glucose metabolism, and a number of lysosomes. The activation of leukocytes, monocytes, and macrophages which is induced by *S. aureus* and treated with areca nut is shown in **Figure 8**.

The areca nut extract probably stimulates the proliferation of macrophages, which in turn leads to the activation of macrophage activity. Further study is needed to find out how extract can increase macrophage activity and capacity.

#### **Figure 8.**

*Intraperitoneal fluid in Giemsa staining. a. The control group showing leukocytes and monocytes, b. Group 2 (500 mg/kg BW) showing an increase in the number of leukocytes, and monocytes, c. Group 3 (1000 mg/kg BW) showing leukocytes, monocytes, and macrophages, d. Group 4 showing macrophages. Mf = macrophage Fagocyte, Mo = monocyte, Leu = leukocyte.*

However, not only is the effect of the treatment given, but the increase in macrophage activity against *S. aureus* infection might also be caused by the internal factor of the macrophage itself. The previous study reported the role of macrophage transmembrane expression that suppressed the *S. aureus*-induced production of nitric oxide and proinflammatory cytokines in mouse macrophages [72]. Moreover, it has been reported by several groups that this bacterium can invade and survive within a variety of cells such as neutrophils, macrophages, T-lymphocytes, epithelial cells, endothelial cells, fibroblasts, and osteoblasts which may be related to the intracellular persistence of bacteria within host cells [73–75]. The markers of biochemical examination (ureum, creatinine, SGOT, and SGPT) did not show changes in liver and kidney in mice after two weeks of treatment and one hour before and post-challenge with *S. aureus*. This study is in line with previous studies which revealed that the areca nut consumed in the long term in humans does not cause hepatotoxicity [76, 77]. However, another study showed that raw areca nut given for 28 days caused mild hepatotoxicity and nephrotoxicity in mice [78].
