Recognition of two epitopes of an antigen present on canine T cells but not on hemopoietic progenitors by four monoclonal antibodies.
Pairs of murine monoclonal antibodies, which recognize 2 different epitopes on a single antigen are described. These antibodies (MdT-P1, -P2, -Q1, -Q2) defining a canine pan-T cell antigen, were raised against dog thymocytes. In immunoblotting of solubilized and polyacrylamide gradient gel electrophoresis in sodium dodecyl sulphate (SDS-PAGE) fractionated dog thymocytes, they revealed a strong heterogeneous antigen. Competitive inhibition of binding of directly labeled mouse-antidog T lymphocytes monoclonal antibodies (MdT-mAbs) to solubilized dog thymocytes indicates that 2 different antigenic epitopes (P, Q) are recognized. In indirect peroxidase immunocytochemistry, MdT monoclonal antibodies recognized up to 95% thymocytes, 69% blood lymphocytes, 76% lymph node lymphocytes, and approximately 2% bone marrow lymphocytes; they were nonreactive with surface immunoglobulin positive blood cells, monocytes, platelets, cells of myelo- and erythropoietic lineage in the bone marrow. Immunohistochemistry on thymus, lymph nodes, and spleen sections revealed that MdT-mAbs had labeled cortical and medullary thymocytes, paracortical T cell areas in lymph nodes and the periarteriolar zone of spleen white pulp, whereas B cell areas remained unstained. The antibodies lysed dog thymocytes in the presence of complement. Lethally irradiated dog receiving bone marrow autograft depleted of MdT-P1 positive cells ex vivo showed engraftment and complete recovery of marrow function. Studies of antibody activity on canine hemopoietic progenitor cells in granulocyte-macrophage progenitors (CFUGM) also showed no reduction of CFUGM in MdT-P1-depleted bone marrow.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000032:analysis / Q000302:isolation & purification; D000918:Antibody Specificity; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D003114:Colony-Forming Units Assay; D004285:Dogs / Q000276:immunology*; D000939:Epitopes / Q000032:analysis*; D005629:Frozen Sections; D006412:Hematopoietic Stem Cells / Q000032:analysis*; D008221:Lymphoid Tissue / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000939:Epitopes