Rosette Formation by Guinea Pig Thymocytes and Thymus Derived Lymphocytes with Rabbit Red Blood Cells¹

Rabbit red blood cells (RRBC) can bind to guinea pig lymphocytes forming rosettes. Ninety-five per cent of thymocytes, about 50% of lymph node cells, 15% of spleen cells, 30% of peripheral blood lymphocytes and <1% of L₂C (B cell) leukemic lymphocytes form rosettes. Lymphocytes with binding sites for complement (EAC rosetting cells) do not rosette with RRBC. Cells sensitive to the cytotoxic activity of anti-thymus derived (T) cell sera plus complement are the same cells that form RRBC rosettes. Anti-T cell sera (even in the absence of complement) inhibit RRBC rosetting. Rosette formation requires a live lymphocyte and is blocked by sodium azide, but not EDTA. It is concluded that the ability to bind to RRBC is a characteristic of living guinea pig T cells and not of B cells.