Therefore, the objectives of this study were to (1) investigate the immune cells phenotype, as well as the phagocytic and oxidative burst activities, in neutrophils in LE and HE dairy cows and (2) assess the in vitro metabolic function of CD4+ T lymphocytes in resting and activated states according to divergent RFI status in dairy cows. The gene discussed is CD4; the disease is hereditary elliptocytosis.