Immune System


The human immune system operates with two distinct arms: i) the innate (or non-specific) immune-type, the first line of defense against invading organisms; and ii) the adaptive (or specific) immune-type, which acts as a second line of defense to provide protection against re-exposure to the same pathogen. The interplay between these two arms of immune system establishes an effective host defense by different functional mechanisms and pathways. The adaptive immune system requires some reaction time to process an invading organism, whereas the innate immune system includes defenses that are constitutively present and readily mobilize upon infection. Also, the adaptive immune system is antigen specific and reacts only with the organism that induced the response. In contrast, the innate system is not antigen specific and reacts universally to a variety of invaders. Finally, the adaptive immune system demonstrates immunological memory, that it “remembers and recognizes” a previously encountered organism and reacts more rapidly on subsequent exposure. In contrast, the innate immune system has no immunological memory.


There is growing evidence that lifestyle factors and dietary behavior are important co-factors in the immune response. Inadequate nutritional intake is the prevailing cause of immuno-compromised host status worldwide. Vitamins, minerals, amino acids, fats and calories are necessary for a balanced immune function. Deficiency of certain nutrients could lead to immune suppression, a condition of inability to produce enough immune cells to protect an individual against infections and allergies. Malnutrition is associated with a significant impairment of cell-mediated immunity, phagocyte function, complement system, antibody levels, and cytokine production. Deficiency of single nutrients also results in altered immune responses: this is observed even when the deficiency state is relatively mild. However, overnutrition and obesity can also influence immune mechanisms. Obesity can promote the development of diabetes, which can alter the immune state. Finally, immunity becomes less effective with ageing and this process is enhanced by associated malnutrition. [Keith & Jeejeebhoy 1997, Chandra 2002, Marcos et al 2003].


Life is a ‘self operating program’ that maintains a fixed cellular/molecular design in an open frame. Openness of this frame, allows physical (i.e. light, temperature) and chemical (in gaseous, liquid, colloidal and solid states) forces pass through its structural space. The “on-or-off” mode of a ‘self operating program’, will govern the ultimate fate (capture, transfer, retention or expulsion) of the physico-chemical encounters from its environment. Continuous transformation of random components of environment into organized segments of a fixed cellular/molecular design will regulate either life or death of an organism. In multi-cellular life forms, humans in particular, the extra-ordinary ability to differentiate ‘self’ from its macro-molecular environmental influx, evolved another vital self operating program – the immune system.

Immune system is designed with a unique computational program to operate four strategic levels of defense management: i) Recognition of non-self, ii) Processing of non-self, iii) Development of memory, and iv) Tolerance to self. These vital characteristics empower the immune response to become scalable, resilient to subversion, robust, and flexible. Also, the host defense needs to be widely distributed, highly responsive, potentially effective and readily degradable in the human body. Self and non-self refer to chemical structures (tissue, cells, molecules, etc) inherent to the body and entities that are encountered through a foreign source, respectively. Immune efficiency is further dependent on the ability to distinguish between harmful non-self (i.e. bacteria, viruses and toxins), and everything else (i.e. food, water and air). The overall success in self defense is contingent upon the ability of the immune system to recognize a large variety of foreign bodies. The system also needs to detect and react to pathogens that the body has never encountered before. Thus, devising efficient defense strategies to discriminate self versus non-self has been pivotal in the molecular evolution of the immune system.


Immune system is based on a multi-layered arrangement of membranes (skin, epithelial, and mucus), cells, and molecules that collectively perform a balancing act, which is lethal enough to kill pathogens or cancer cells, yet specific enough not to cause any collateral damage to “self”. Accordingly, immunity is a super intelligent process that deals with a magnificent variety of unknowns in the environment.