Enumeration of Absolute Numbers of T and B Lymphocytes in Human Blood

A new immunofluorescence test permits the direct enumeration of T and B lymphocytes in unseparated blood. B cells were identified with antiimmunoglobulin sera and T cells by a rabbit anti-human brain serum rendered unreactive with B cells by sequential absorption with erythrocytes, liver, and either chronic lymphocytic leukaemia cells or a cell line, BRI-8, with B-cell surface characteristics. T and B cells were also enumerated with lymphocyte suspension purified by either Ficoll-lsopaque density sedimentation or by a two-step gelatin-polystyrene bead column method. T cells in Ficoll-purified suspension were also enumerated by rosette formation with sheep erythrocytes. Comparison of the T-B proportions evaluated with the different cell preparation showed that the cell separation procedures can give rise to a deviation in the T:B ratio in favour of B cells. The extent of this induced bias related inversely to lymphocyte yield. Staining of whole blood preparations or high-yield purified cells enables absolute numbers of T and B lymphocytes to be calculated. We consider this measurement considerably more informative than relative proportions of T and B cells.