Self‐Reactive Delayed Type Hypersensitivity Induced in Mice by Syngeneic Lymphoblasts: II. Isolation of Two Distinct Lymphoblast Antigens, One of Which Reacts (or Cross‐Reacts) with Anti‐H‐2D^d Monoclonal Antibody

X‐irradiated (250 rad) or normal A mice injected with syngeneic concanavalin A‐induced lymphoblasts (syn‐Con A blasts) developed an inflammatory response in their footpads 24 to 72 h after injection of syngeneic lipopolysaccharide induced lymphoblasts (syn‐LPS blasts) into these tissues. This immunological activity was designated syngeneic delayed type hypersensitivity (syn‐DTH), because T cells transferred the response to naive recipient. Analysis on Ultrogel or Sephedex G‐50 columns revealed that a Con A‐blast extract contains two syn‐DTH‐stimulating antigens: a small antigen (6000–7000) and a large antigen (apparent MW of 160,000–175,000). This conclusion held true even when protease inhibitors were included in the fractionation procedure. The approximate molecular weights of these antigens estimated by that gel filtrations were confirmed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE). The large lymphoblast syn‐DTH‐stimulating antigen contains carbohydrate residues but not products of the H‐2 genetic region. The small antigen does not contain sugar moieties, but it expresses affinity to anti‐H‐2D^d monoclonal antibody. The immune response to the small antigen but not to the large antigen is genetically restricted at body the induction and the elicitation in phases of the DTH. A strain of mice immunized with the small antigen generated syn‐DTH after challenge with lymphoblasts of B10.T (6R) mice, which share the H‐2D^d subregion with A mice but not the H‐2K or the H‐2I subregions. Fast protein liquid chromatography of the small antigen yielded a purified material which appeared as a single band after Coomassie staining of its gel electrophoresis.