Artificial Immune System

Artificial Immune System or AIS can be explained as metamorphic or abstract computational system utilizing ideas gleaned from components of immunology and theories. Artificial Immune System aims to resolve a broad range of jobs concerned to complex computational and engineering problems as like: pattern recognition, combinatorial optimization and machine learning. In current years, research on Artificial Immune System has captured the attention of different researchers attempting to solve common combinatorial problems. Each living organism exhibit several sort of defense mechanism against foreign attack of harmful cells or disease. "The major function of the immune system to recognize all the cells in the body and classify them into non-self and self cells". The immune system or IS of a living being consists of various molecules, organs and cells, spread via the body. There is nothing as like central controlling organ for immune actions. There are some elements moreover in transition for example: blood stream or in different stationary cells for example: thymus, showing their complementary roles. The immune system or IS identifies the malfunctioning and harmful cells causing elements. Any of molecules such can be identified by the immune system are termed as antigens. There are two kinds of antigens: non-self and self. Self-antigens initially belong to our own body and are harmless cells in their functioning such while non-self antigens are disease- causing elements. Several receptor molecules are there upon the immune cells surface, that are able of recognizing roughly limitless range of antigenic patterns. There are two main types of immune cells as: T- and B-cells. These cells are as the same in nature, however differ in the manner they recognize antigens. Antigens free in solution for example: blood stream, such can be identified by B-cells, while T-cells identify antigens present in other accessory cells. Whilst an animal is exposed to an antigen, several sub-population of its bone marrow derived cells B-lymphocyte reacts by producing antibodies. Antibodies are molecules shown on the surface of B-cells that identify and bind to an antigen. Hence, there is no distinction among B- cells and its receptor, antibody. Recognition or identification of an antigen is essential for the immune system or IS to as active and present consequent response. The recognition or identification can merely be activated, whether the cell receptor recognizes an antigen along with affinity greater than affinity threshold. Afterward T-cells are generated; they migrate into the thymus, an organ situated behind the breastbone whereas they are matured. Throughout maturation all self-antigens that are recognized via T-cells are eliminated from the population of T-cells. Such process is called as negative selection. If a B- cell encounters a non-self antigen along with an appropriate affinity-threshold, this distinguishes and proliferates in effecter cells and memory; a process termed as clonal selection. In contrast, if a B-cell identifies a self-antigen, this may show to suppression, as like recommended via the immune network. The adaptive biological evolution process and the antibodies production are strikingly the same considering such the two central processes occupies in the production of antibodies, genetic mutation and recombination, are the similar ones causes for sexually reproducing species' the biological evolution. The functioning of the immune system or IS rather powerful as this can store memories of past experiences in language of the strengths of the interactions of its constituent cells. This can produced also responses to innovative antigens patterns. The generic code of artificial intelligent system is described in figure.

Representation and Initialization POP

Define                        Problem specific objective function

Maintain                     randomly generated initial POP of antibody.

Exposure                    of initial population    to the threats  posed   by antigens.

Randomly choose        an antigen (Agj ?  Agm) and expose it to all antibody

Determine                  the affinity fk  of the entire antibody in relation to Agj.

Interaction                 between antibodies

Select                       n highest affinity antibody.

Make                         a new set of selected antibody.

Cloning                        of Selected  antibody proportionally to their antigenic affinity, Ck.

Hypermutation

New population           Ck* of matured clones is generated  by doing hypermutation.(Higher the affinity, lower the mutation rate.)

Determine                   the affinity fk* of the matured clones. Now all the antibodies are selected to compose the memory.

Choose                       the best antibodies Abd  by replacing d lowest- affinity antibody.

Repeat                       the process, until termination criteria is not satisfied.

                                    Figure 5: Step-wise Procedure of Artificial Immune System