[Immune system and diseases that vary with circumstance and physical condition]

Empirically we all know that our immune system varies depending on environmental factors and physical conditions. However, such recognition has remained at an empirical level for a long time without the accumulation of scientific data. The major reason is that the substance and its receptor that connect physical conditions with the immune system have previously been obscure. Adrenergic and cholinergic receptors on leukocytes may be important in understanding that relationship. Furthermore, we have to consider the mutually antagonistic functions of granulocytes and lymphocytes in the body. All stimuli from environmental factors change our physical conditions and subsequent changes in the autonomic nervous system influence our immune system through adrenergic receptors on granulocytes and cholinergic receptors on lymphocytes. Overactivation of granulocytes induces purulent diseases or tissue destruction, whereas overactivation of lymphocytes induces allergic diseases.