Reduction of the content of fibronectin in blood plasma depending on severity and form of the disease was revealed in patients with infection-dependent bronchial asthma. Discreteness of influence of autologous leucocytes upon the concentration of fibronectin in plasma, caused by the factor of hormone dependence of the disease was discovered. It was determined that tactivin recovers capability of leucocytes in the patients with hormone dependent asthma directly (monocytes) or indirectly (Lymphocytes, neutrophils) to produce fibronectin.