RESUMEN
<p><b>OBJECTIVE</b>To investigate the effects of extremely low frequency magnetic and electric fields (ELFEMFs) emitted from 380 kV transmission lines on some leukocyte differentiation antigens in dairy cows.</p><p><b>METHODS</b>The study was carried out in 5 cows exposed to 1.98-3.28 microT of ELFEMFs and in 5 control cows exposed to 0.2-0.7 microT of ELFEMFs. Following haematological and immunologic parameters were measured in both groups: WBC, CD45R, CD6, CD4, CD8, CD21, and CD11B leukocyte antigen expression.</p><p><b>RESULTS</b>Some of the haematological and immunologic parameters under investigation were similar in both groups. However, CD8 (T lymphocyte surface antigen) was higher in the exposed group (1.35 +/- 0.120 vs. 0.50 +/- 0.14 x 10(3)/mL). Furthermore, the CD4/CD8 ratio (0.84 +/- 0.05 and 2.19 +/- 0.16 for exposed and not exposed cows respectively) and circadian rhythm were different between the two groups.</p><p><b>CONCLUSION</b>Exposure to ELFEMFs is responsible of the abnormal temporal variations and distribution of some haematological and immunological parameters in dairy cows.</p>