This study was conducted to monitor the early physiological events during
the initiation of the humoral immune response. This would eventually benefit the
development of superior poultry immunization program. One hundred and twenty male
white Leghorn cockerels aged eight-week-old were injected intravenously with either
0.5 ml of 10% sheep red blood cells (SRBC), a T-dependent antigen, or saline. Blood
samples were collected at O. 1, 3, 6. 9 and 24h foll9wing the injection. Total white
blood cells (WBC), differential counts, corticosterone, T₃, T. and glucose
concentrations were measured in all blood samples. Total WBC counts. lymphocytes (L) and monocytes decreased significantly
at 3. 6 and 9h post SRBC injection. However, Circulating heterophils (H) and HIL ratio
increased significantly at 1, 3. 6 and 9h post SRBC injection. Serum corticosterone and glucose concentrations increased significantly at
3h and 6h and at 3 h post SRBC injection respectively. On the other hand, serum T3
and T4 decreased significantly at 3h post SRBC injection. There were no significant changes in total WBC count, lymphocytes and
heterophils count, serum corticosterone and glucose levels following saline injection.
However, monocytes decreased significantly at 6h and 9h. T. decreased significantly
at 3h. while T3 increased at 1h post saline injection as compared to Oh. These results showed that injection of the T-dependent antigen, SRBC,
initiates a wide variety of hormonal, immune logical and metabolic changes in the
chickens. These changes may explain the Interaction between the neuroendocrine
and immune system.