Evaluation of the cell-mediated immune response of chickens vaccinated with Newcastle disease virus as determined by the under-agarose leukocyte-migration-inhibition technique

The under-agarose leukocyte-migration-inhibition (LMI) assay for the evaluation of cell-mediated immunity (CMI) was developed for use in chickens. A significant CMI response was demonstrated in chickens vaccinated with Newcastle disease vaccine by using this assay. The results also indicated that the under-agarose LMI test was a reproducible and relatively easy assay to perform. Serological antibody titres were determined to study the correlation between haemagglutination-inhibition (HI) titres and LMI levels using the HI microassay. The presence of the CMI response was always correlated with the presence of the serological immune response and vice versa. However, the quantitative level of the CMI response did not always correspond to the quantitative level of the serological immune response. From the results of this study it was not possible to predict humoral antibody level on the basis of a CMI response and vice versa.