Interrelationship between Heat Shock Protein 70 (HSP70) and LymphocyteProliferation in Thermal Exposed Buffalo Heifers

Abstract

Effect of thermal exposure on induction of Heat Shock protein–70 (HSP70) was assessed in Murrah buffalo heifers after exposure at 450 C for 4 h in a climatic chamber. Physiological cardinal responses were measured pre-exposure, 2 h after exposure and 4 h after exposure and jugular vein blood samples were collected. Rectal temperature (RT) of buffalo heifers increased from 38.16+0.200C to 40+0.240C, pulse rate (PR) from 39+1.00 to 70+4.00 beats/min and respiratory rate (RR) from 18+1.00 to 54+2.00 breath/min after 4 h of exposure at 450C indicating that exposure was stressful. The rise in RT, PR and RR was significant at 2 h (P<0.001) and 4 h exposure (P<0.001). Heat Shock protein-70 (HSP70) and Interleukin 2 (IL–2) was assayed in the plasma of exposed heifers and lymphocyte proliferation assay was performed using whole blood method. HSP70 level in the plasma was found to be 1.42+0.10, 2.25+0.54 and 1.76+0.30 ηg/µg of protein at pre exposure, 2 h exposure and 4 h exposure, respectively. The concentrations of IL–2 and lymphocyte proliferation were highest during the pre exposure period, but HSP70 concentration was lowest prior to the exposure of heifers. No correlation was observed in between HSP70 and IL–2 and a negative correlation was observed in between HSP70 and lymphocyte proliferation. A positive correlation was observed between IL–2 and lymphocyte proliferation. The study indicated that thermal exposure of buffaloes caused induction of HSP70 and declined the immune status of buffalo heifers.