**2.3. Cytokines**

Cytokines are a diverse group of intercellular signaling peptides and glycoproteins with molecular weight between 6000 and 60,000. They are produced by a variety of tissues and cells in response to stimuli [2]. Cytokines have diverse and pleiotropic effects [4]. Their binding to specific receptors on the cell surface leads to changes in growth, development or activity of the target cells. They do not only regulate immune and inflammatory responses but also involve in wound healing, haematopoiesis, angiogenesis as well as other biologic processes [2, 4].

The diagram shows the mechanism of regulation of immune response. Th1 is mainly involved in cell-mediated im‐ munity and offers protection against intracellular pathogens while Th2 is important in humoral immunity, protection against helminthic infection as well as allergic or atopic diseases such as allergic rhinitis, asthma etc.

**Figure 1.** The regulation of immune response [3]
