Effect of route of inoculation on humoral immune response of white leghornchickens selected for high or low antibody response to sheep red blood cells

Effects of route of SRBC inoculation and antigen dosage on primary and seco ndary antibody response of White Leghorn lines selected for high (HA) or lo w (LA) 5-d antibody response to a single i.v. inoculation with 0.1 mL of a 0.25% a suspension of SRBC were studied in two trials. In the first trial, chicks from parents of generation S-24 of each line were randomly assigned to one of four treatments. At 35 d of age, they were inoculated into the br achial vein with 0.1 mL of 0.25% suspension of SRBC or into the breast musc le with 0.1 mL of 0.25, 2.50, or 25.00% SRBC. Plasma SRBC antibody was meas ured 3, 6, 10, and 20 d later. In the second trial, chicks from parents of generation S-25 of each line were randomly assigned to treatment groups. At 28 d of age they were inoculated with 0.1 mL of 0.25% SRBC into the brachi al vein, 0.1 mL of 25.00% SRBC into the thigh (T-L) or breast muscle (B-L), or 0.5 mL of 25.00% SRBC into the thigh (T-H) or breast muscle (B-H). Twen ty-one days later, chicks (except five per group) were given a booster inoc ulation of 0.1 mL of 25.00% SRBC into the thigh muscle. Six and 10 d after each inoculation, plasma SRBC antibody, IgG, and IgM titers were measured. The SRBC antibody titers after primary i.v. inoculation with SRBC were alwa ys higher for HA than LA chicks. When inoculations were i.m., differences b etween lines varied with dosage. Low dosages inoculated into the breast fai led to induce line differences consistently, whereas at higher dosages, tit ers were greater for HA than LA chicks regardless of inoculation site. For Line LA, inoculation into the thigh elicited higher titers than inoculation s into the breast. Antibody titers to the booster inoculation of SRBC were similar for the lines.