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

Effect of thermal exposure on induction of Heat Shock protein-70 (H5P70) was assessed in Murrah buffalo heifers after exposure at 45 degrees 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+0.20 degrees C to 40+0.24 degrees C, 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 45 degrees C 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 eta g/mu g 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.