Having adequate immunity fights against allergy and infections. Immunity is of two types namely innate and adaptive immunity. Humans immune system produces micro-inflammation against host invading body. Immunogenetics deals with the study of the interrelation of autoimmune disorders, infectious diseases. Based on previous studies on skin infections it has been found that bacteria is cause for hypersensitivity reactions. The effect of the pathogen on host depends upon the virulence factors. Bacteria acts as an antigen to the human immune system and bacterial peptides undergo exocytosis get attached to MHC-II.