T. M. Bryzgina, L. I. Aleksyuk, T. V. Martinova, V. S. Sukhina, I. N. Alexeyeva THE EFFECTS OF INHIBITORS OF CYCLOOXYGENASE AND LYPOXYGENASE PATHWAYS OF OXYDATION OF ARACHIDONIC ACID ON THE IMMUNE RESPONSE, AND THE ACTIVITY OF MONOOXYGENASE SYSTEM AND LIPID PEROXIDATION IN MICE In experiments on CBA mice we studied an immune response (IR) to sheep red blood cells, the activity of monooxygenase system and lipid peroxidation (LP) in a spleen and a liver after administration of indomethacin (IND) and nordihydroguaiaretic acid (NDGA) as the inhibitors of cyclooxygenase and lypoxygenase pathways of oxydation of arachidonic acid consequently. We have found that the both inhibitors changed differently the intensity of IR during its development. IND and NDGA activate the accumulation of antibody-forming cells in the mouse spleen in a dose- dependent fashion at both the inductive and fading phases of IR. At the productive phase these changes are less expressed and they are different depending on the dose of NDGA: the smaller dose increases the immune response and the bigger one decreases it a bit. Changes in the activity of the monooxygenase system in spleen and liver, affected with the both inhibitors, independing on the dose, were of different direction: after IND administration the activity increased, but after NDGA administration it decreased at all the terms of investigation, excluding the term of the 5-th day (productive phase of IR). In these conditions changes in the activity of IR were of opposite direction as compared to the changes in the monooxygenase system. A. A. Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kiev