Mastitis is one of the most economically significant diseases in the dairy cattle industry, which increases treatment costs and reduces milk production, genetic advancement of the herd, and reduced milk quality. In the present study, the expression level of some influential genes involved in the immune system as well as disease including lactoferrin, CD74, glycosylation dependent cell adhesion molecule 1, and FCER1G genes were investigated. For this purpose, the breast tissue was separated from 10 cows with clinical mastitis and 10 healthy cows and total RNA was extracted from epithelial cells of mammary tissue of healthy and diseased cows using a kit. Then cDNA was synthesized using kits and the relative expression of the genes was measured using the real-time PCR technique. The 18S rRNA gene was used as a housekeeping gene. The relative expression of genes was measured by the 2-ΔΔct method and statistical differences between healthy and patient groups were examined by t-test. The results showed that the expression levels of Lf, CD74, and FCER1G genes in the group of cows with clinical mastitis were 2.5 (P<0.0003), 6 (P<0.0004), and 2 (P<0.002) times higher than healthy cows, respectively. In contrast, the expression level of the GLYCAM1 gene was significantly lower (4 times) in the group of cows with clinical mastitis comparing healthy cows (P<0.0074). Given the important role of these genes in immune responses, it is important to study them as candidate genes for resistance to mastitis disease. پرونده مقاله