Normally the antibodies formed or the cells activated against a particular infecting agent are protective. That means they try to neutralize the effect of pathogenic organisms. Sometimes in doing so, the Anaphylaxis is an immediate type of hypersensitive reaction. Many chemicals like egg albumin, penicillin G, B-complex may also damage the host tissue. Such type of altered reactivity, leading to injury to the host tissue is called hypersensitivity. injections, can cause anaphylaxis. Type III hypersensitivity occurs with soluble antigen. Antigen and antibody complexes are commonly formed in response to a wide range of microbial infection or foreign antigens. These complexes are usually cleared by phagocytic cells without causing any damage to the host. Delayed hypersensitivity was first demonstrated by Robert Koch in relation to tuberculosis.