Effect of different doses of sheep erythrocytes on the humoral immune response of chicken lines selected for high or low antibody production.

ABSTRACT

A study was conducted to determine the influence caused by the dose of sheep red blood cells (SRBC) on the humoral response of chicken lines selected for high (H) or low (L) antibody production to SRBC. The chicks were of the 5th selection generation. Both sexes were used. The primary doses of SRBC used were 5 x 10(-4), 5 x 10(-3), 5 x 10(-2), 25 x 10(-2), and 5 x 10(-1) mL packed cells, suspended with phosphate-buffered saline (PBS) to 1 mL, and injected intramuscularly (im). All chicks were reimmunized im with 5 x 10(-1) mL packed cells in 1 mL of PBS. Throughout the experiment, H line chicks had higher titers than L line chicks. The level of primary total and 2-mercaptoethanol (2ME)-resistant titers followed the dose level. However, in total titers, the interactions between line and dose were seen at days 3 and 5 postimmunization. This was caused by a deviation in the ranking of the doses in the L line. Moreover, the kinetics of the primary response differed between the lines. Generally, in H line the peak number for the titers was reached earlier in the response period. The optimum response in terms of the total number of titers in the secondary response generally was inverse to the primary dose level. However, from Day 7 of the secondary response onward, the dose effects were influenced by line. For Line L, no effects for dose on the responding antibody level was seen. The 2ME-resistant titers followed the dose level in the secondary response.(ABSTRACT TRUNCATED AT 250 WORDS)