Inflammatory lymphoid cells. Cells in immunized lymph nodes that move to sites of inflammation.

The arrival of cells from normal and immunized lymph node cells at sites of inflammation was studied. Mice were immunized with oxazolone' or picryl chloride and 3–4 days later the draining lymph node cells were dissociated, labelled with Cr and injected intravenously into recipients. Sites of inflammation were produced in the recipients by painting the ear with chemically reactive contact sensitizing agents or croton oil. The net arrival of normal lymph node cells at sites of inflammation was 0.1 per cent. In contrast the arrival of cells from immunized lymph nodes was 4–8 times greater. The peak number of cells that moved to sites of inflammation occurred 4 days after immunization with oxazolone'. An increase in the percentage of cells that moved to sites of inflammation occurred in lymph nodes after immunization with a number of agents including contact sensitizing agents, skin grafts and Freund's complete adjuvant. There was little or no increase in mice rendered unresponsive to picryl chloride and then immunized with picryl chloride or in mice injected with aluminium hydroxide, alum precipitated mouse serum or pneumococcal polysaccharide. This suggested that immunization and possibly the induction of delayed hypersensitivity was necessary for the generation of these cells. The arrival of the cells did not depend on antigenic similarity between the agent used to immunize the lymph node and the agent used to produce inflammation. For example increased arrival of cells from immunized lymph nodes occurred at sites of inflammation produced in the ear by croton oil or in the peritoneal cavity by paraffin oil.