The function of the immune system is to defend the individual from various sources of infections such as different types of virus, bacteria, fungi, protozoa etc. At the same time it protects the body from the damage inflicted by the foreign antigens, by recognizing and eliminating those antigenic determinants or epitomes, which are not present in the self.
As a whole immunity can be defined as the defensive mechanism of our body that resists infection. Immunity may be inherited or acquired. Inherited immunity comes from genetic inheritance through placental circulation during intra-uterine life and through lactation afterbirth.

    The acquired immunity can be artificial or natural. The natural acquired immunity develops from repeated minimal infection. The artificial acquired immunity is of two types namely active and passive.
Active artificial acquired immunity occurs from introducing bacteria,virus or their products like toxins and haptens. Passive artificial immunity develops by introducing readymade antibodies from immune serum.

What is hapten?
    These are non protein, non antigenic substances, which after introduction in to the body system stimulate the endogenous proteins to act as an antigen against which antibodies are formed. Study has proved that the homoeopathic medicines act like haptens & play an important role in the production of antibodies by stimulating the endogenous protein.

Hapten and Homoeopathic Medicines
    We know that minimum infection produces immunity and maximum infection causes disease. Both these theories taken together forms the basic of immunology. Therefore in order to prevent or cure a disease Homoeopathically minimum stimulus that is sufficient to excite a reaction in the system is needed. The potentised Homoeopathic medicines are capable of curing diseases by production of immune bodies. Following is the scientific explanation of Homoeopathic cure in the light of immunology as stated by renowned physician Dr. S.P Dey –

    “The Homoeopathic medicines act through the vital force on the endogenous proteins to act as antigens, against which antibodies are formed. During this phase a similar but stronger disease tends to be produced in the system, but meanwhile antibodies start forming against the Homoeopathic medicines and acts like hapten. The haptenic antibodies jointly with the antigenic antibodies counteract the disease antigen and the patient gets cured.”.