Transfer of an antigen-specific immediate hypersensitivity-like reaction with an antigen-binding factor produced by T cells.

The fact that T cell-dependent activation of mast cells occurs in delayed-type hypersensitivity led us to investigate whether a T cell product could mimic some of the functions of IgE. We report that 24- or 48-hr cultures of T cells from mice immunized optimally for delayed-type hypersensitivity resulted in release of an antigen-binding factor that transferred the ability to elicit an antigen-specific immediate hypersensitivity-like skin reaction in normal recipients. The responsible factor was concentrated and purified by affinity chromatography on antigen columns and was distinguished from immunoglobulin by several criteria: (i) it was released by purified T cells (anti-immunoglobulin plate depletion of B cells); (ii) it expressed no known antigenic markers of immunoglobulins (enzyme-linked immunosorbant direct binding assay); (iii) it had a molecular weight of 70,000 or less (sucrose gradient ultracentrifugation); and (iv) it had serological markers associated with antigen-specific T cell factors from other experimental systems. We suggest that, at sites of delayed-type hypersensitivity, antigen-reactive T cells may release antigen-specific factors that lead to mast cell activation and release of vasoactive amines, which is required for elicitation for these responses.