Tamoxifen decreases level of immunoglobulins in blood of the hen (Gallus domesticus) without alteration in non-immunoglobular fractions of plasma proteins

Summary The effect of tamoxifen (TMX), an anti‐estrogen compound, on immunoglobulins (Ig) level in blood plasma of laying hens was investigated. TMX (4 mg/hen/day) was given per os for seven consecutive days; control hens received placebo. Blood samples were collected from the wing vein every day before TMX treatment, and plasma Ig levels were measured by means of Ślebodziński's test. TMX significantly decreased plasma Ig levels, maximally by 51% on day 2 of the experiment. The observed reduction in Ig level was accompanied by the significant, 37% decrease in the ratio of Ig/total protein (Tp). From the third day of TMX treatment, level of Ig and the ratio of Ig/Tp gradually increased and on the day 5 of the experiment no difference between control and experimental group was found. In non‐immunoglobular (Tp‐Ig) fractions of plasma proteins no significant alterations after TMX treatment were observed. Therefore, treatment of laying hens with TMX transiently decreased plasma Ig levels. Most likely the effect of TMX is associated with the antagonistic properties of TMX toward estrogen receptors. On the contrary, the transient decrease in plasma Ig levels of TMX‐treated hens followed by the gradual increase suggests adaptation of the immunological system to treatment with the anti‐estrogen preparation.