Fluorescence analysis and anatomic distribution of mouse T lymphocyte subsets defined by monoclonal antibodies to the antigens Thy-1, Lyt-1, Lyt-2, and T-200.

Abstract

Abstract The distribution and anatomic localization of T cell subpopulations defined by monoclonal anti-Thy 1, T-200, Lyt-1, and Lyt-2 antibodies were studied by flow cytofluorometry and immunohistologic methods. Both normal mice and cortisone-treated mice were used in the present study. In the normal thymus, the large majority of cortical cells are brightly Thy-1+, T-200+, and Lyt-2+, whereas the Lyt-1+ cells in the cortex show a wide range of antigenic density variations. Most cortical lymphocytes, however, are dull Lyt-1+. Lymphocytes located in the medulla are dull Thy-1+ and T-200+, whereas most are brightly Lyt-1+, but negative for Lyt-2. Cortisone treatment has 3 major effects on the frequency and distribution of T cell subpopulations in the thymus. First, the population of cortical lymphocytes is severely reduced within 2 days after injection, resulting in a relative increase in the population of dull Thy-1+, bright Lyt-1+ (Lyt-2−) cells. Secondly, many bright Thy-1+ cells are located in the outer cortex of the thymus of cortisone-treated mice. Serial cryostat sections incubated with anti-Lyt and anti-T 200 antibodies show that most of these cortical cells are negative for T-200, Lyt-1, and Lyt-2 determinants. Third, the subcapsular region of the thymus contains a small population of lymphoblasts that are virtually negative for all tested antisera. Peripheral lymphoid organs and cells in the thoracic duct are less affected by cortisone treatment. It appears, however, that the frequency of Thy-1+ and Lyt-1+ cells in the spleen, but not in the lymph nodes and thoracic duct, decreases after cortisone treatment. In the spleen and mesenteric lymph nodes of normal mice, typical B cell domains such as germinal centers and follicles contain a few Thy-1+ cells. Serial sections incubated with anti-Lyt 1 antibodies always show a higher frequency of Lyt-1+ cells than Thy-1+ cells, indicating the presence of Thy-1−, Lyt-1+ cells in B cell domains. In the mesenteric lymph nodes, T-200 is strongly expressed on both T and B cells, whereas most blast cells in germinal centers are T-200 negative. T-200 determinants were also found on a subpopulation of blast cells in the red pulp of the spleen. The present results on the distribution of T cell subsets are discussed in the light of new data on the differentiation of the T cell system.