Ki-T1R detects an epitope of a 161kD glycoprotein (4 bands of 36kD, 38kD, 40kD and 47kD under reducing conditions) which is located on the outer surface of cytoplasmic membranes. Antigen distribution: Isolated cells: Ki-T1R detects approximately 80 % of peripheral blood T-cells. It is negative on all other cell types. Tissue sections: Ki-T1R shows very characteristic staining patterns in lymphoid organs according to the T-cell distribution, paracortical T-cell zone of lymph nodes, periarteriolar T-cell zones of the spleen, T-cell nodules of the gastrointestinal tract and bone marrow, thymocytes with prevalence from thymus medulla. Specificity: Rat: T-lymphocytes Other species: not tested.