Leukotrienes are part of a class of biologically active compounds that occur naturally in which type of body cells?

Leukotrienes are part of a class of biologically active compounds that occur naturally in the white blood cells or the leukocytes. These compounds functions in the pathogenesis of inflammation. They trigger the contraction of the smooth muscles located in the bronchioles. Excess amounts of this substance is a cause of the inflammation during asthma and in allergic rhinitis.  

No you are not wrong