IgG and IgM responses in high and low antibody-selected lines of chickens.

Kinetics of IgG and IgM as measured by 2-mercaptoethanol-resistant (MER) and susceptible (MES) antibodies to sheep erythrocytes, respectively, were determined as correlated responses in lines of chickens selected for high (HA) and low (LA) antibody response to sheep erythrocytes. Primary response patterns for total, MER, and MES antibody differed according to the genetic line. Total antibody increased rapidly, peaked, and persisted at moderate levels in line HA, whereas both peak and persistency were lower in line LA. Levels of MES peaked and then declined in line HA chickens but persisted at low levels throughout in line LA. Titers of MER antibody were considerably greater in line HA than in line LA both on an absolute basis and as a proportion of total antibody titer. Secondary total titers were greater at five days after injection than at three days and greater for line HA than for line LA chicks. The pattern observed for MER and MES in line LA was similar to that for total antibody, as was MER in line HA. For MES the pattern was reversed in line HA.