Tissue distribution and ontogenic appearance of a chicken T lymphocyte differentiation marker

Abstract

A monoclonal antibody, designated T₁₀A₆, was produced by immunizing mice with H. Bl4 chicken thymocytes. T₁₀A₆, when tested by immunofluorescence, labeled 80% of thymocytes, and a subset of peripheral T cells: 20% of spleen leukocytes, 10% of blood leukocytes, 8% of bone marrow cells but less than 1% of bursal lymphocytes. Tissue distribution on polyethylene glycol sections showed that in the thymus T₁₀A₆ stained most cortical thymocytes and a portion of medullary cells. In the spleen, the positive cells appeared scattered mainly in the T‐dependent areas. Ontogenic studies revealed that the antigen recognized was found in the chick embryo thymus from day 11 onward and the expression of this antigen on thymocytes reached the adult level from day 13. The first positive cells were detected in the spleen on day 13 of embryonic life. T₁₀A₆ (IgG₁) precipitated a 65‐kDa material from thymocytes. This is the first description of a monoclonal antibody recognizing a peripheral T cell subpopula‐ tion in chicken.