Immunomodulation and 'Ia' variability in dendritic lymph cells: a radiobinding immunoassay versus immune response study.

A radiobinding immunoassay technique has been employed to determine the 'Ia' antigens localised on the surface of the following immunocompetent cells: Dendritic lymph cells from peripheral intestinal lymph, peritoneal macrophages and thymocytes all gathered from sheep red blood cell treated animals, and the irradiated cell controls. A corresponding popliteal lymph node assay was performed following the administration of the same cells into the foot pad of allogeneic rats to determine the comparative immunogenic responsiveness. Dendritic lymph cells in free flowing lymph of sensitised, irradiated and control animals showed a significantly higher 'Ia' content and consequently greater immunogenicity as measured by the popliteal lymph node assay. Sheep red blood administration in animals may stimulate surface 'Ia' expression in lymph derived dendritic cells resulting in higher immune-responsiveness.