Antibody responses and body weights of chicken lines selected for high and low humoral responsiveness to sheep red blood cells. 1. Effect of Escherichia coli lipopolysaccharide.

Antibody (Ab) responses to i.m. administered SRBC and BSA, and i.p. administered Escherichia coli lipopolysaccharide (LPS), and BW at various times after treatment, were measured in chicken lines divergently selected for high (H) and low (L) Ab responses to SRBC, and in a randombred control line (C). The Ab responses to SRBC and BSA, but not LPS, were significantly affected by line by treatment interactions. Levels of antibodies to SRBC and BSA were higher in the H line than in either the C or L line (P < 0.05). Administration of LPS did not affect Ab responses to SRBC, but Ab responses to BSA were decreased in birds that received BSA and LPS simultaneously. Body weights of C and L lines were significantly higher than BW of H line birds at all times. Lipopolysaccharide injection induced an acute, but transient reduction of BW gain, which was not affected by line. Antibody responses to SRBC and BSA were negatively correlated with BW. During the experimental period, however, percentage BW gain and humoral responsiveness were positively correlated. A higher percentage BW gain growth was seen in H line birds at the end of the experimental period. The present results confirm the hypothesized acute cachectin nature of LPS, but the relationship between live BW (gain) and immune responsiveness in chickens remains to be further clarified.