The immune system: a delicate balance

Composed of a set of cellular components interact with each other, the immune system is in unstable equilibrium, which may lead to hypersensitivity reactions such as allergy if it becomes too active, or the opposite, immune deficiencies are resulting in infections, immunological diseases and cancer, agreed to say specialists immunity present at a debate organized by the Wyeth Foundation Professors Alain Fischer and Jean-Laurent Casanova (Necker Hospital, Paris) and Professor Patrick Berche (University Paris V).
The immune system, whose function is to distinguish the components of "self" and "non-self" by attempting to eliminate them, has developed two mechanisms interrelated and influence each other:

- Innate immunity: active from birth, it requires no prior contact with a pathogen and does not induce immunological memory;

- Specific immunity: acquired over the months she has learning ability, adaptability and memory.

There is not one but a hundred-induced immune deficiency, and to speak differently depending on the individual diseases.

Most of primary immune deficiency diseases (affecting four cell groups, B lymphocytes, T, phagocytic cells and complement system) are genetic, while those induced by secondary immunodeficiency fall of a breach of secondary to an immune system disease, radiation, chemotherapy or malnutrition and sometimes reversible. AIDS, for example, is a secondary immunodeficiency caused by HIV.

A child born in 5000 in France each year with an immune deficiency. The resulting diseases are expressed differently depending on the nature of the deficit, age, sex or ethnicity. Nearly 100 different specific primary immune deficiencies have been identified: 70% are deficient in B lymphocytes, 20% deficient in T lymphocytes and 10% received both cell populations.

Other hereditary defects on neutrophils are primarily diagnosed in infants, children and adolescents: 80% are under 20 years old and 70% are male. In addition, 150 new cases are discovered each year in France.

Although the origin of immune deficiency is often linked to a single gene, we still do not know the exact causes of primary immunodeficiencies, the interaction between genetic and environmental factors may play a role. Problems intrauterine development are also discussed, even a drug administration (phenytoin deficits immunoglobulin A).

One of the most important functions of the immune system is to protect the body, the immune-deficient patients generally have an increased susceptibility to infections of all types. Many, abnormally frequent and severe, they can be located in the bronchi, lungs, intestines, skin or mucous membranes. Thus, the resistant thrush may be the first sign of T cell immunodeficiency In children, may also be noted stunted.