The migratory behavior of T blasts to contact sensitivity reactions in activelyand passively sensitized mice.

The arrival of cells from lymph nodes immunized with the contact sensitizing agents oxazolone and picryl chloride at ears challenged with these antigens was studied inmice using the technique of labelling with -51Cr. An apparent specificity of arrival was seen because the immune cells transfered contact sensitivity passively, giving rise to an inflammatory response in the ear, to which a subpopulation of cells (T blasts) was non-specifically attracted. It was also shown that there are at least two distinct populations of cells with the ability to move to inflammatory sites: the first, found in immunized lymph nodes, moves to contact sensitivity reactions in both actively and passively sensitized mice; the second, found in bone marrow and oil-induced peritoneal exudates, moves to contact sensitivity reactions in actively sensitized mice, whereas in passively sensitized mice, the arrival of these cells at contact sensitivity reaction is poor. It is suggested that the ability of T blasts to move to sites of inflammation my be useful as an assay technique for contact sensitivity reactions.