Separation of non-proliferating from proliferating thymic lymphocytes based on light scatter analysis.

Two populations of thymic lymphocytes from eight-week-old mice were separated based on the light scatter intensity they generated while passing through a flow cell analyser. The two populations were subsequently studied morphologically and analysed for the relative amount of DNA present in each cell. Cells having a low light scatter intensity had a high nuclear:cytoplasmic ratio, a heterochromatic nucleus, and a proliferative index (S + G2 + M) of only 23%. Cells with a high light scatter intensity had a low nuclear:cytoplasmic ratio, dispersed chromatin, frequently a uropod with budding microvilli and a proliferative index of 71%. The low light scatter cells resemble small cortical thymocytes or lymphocytes from the thoracic duct described by others. The highest light scatter cells resemble medium lymphocytes shown by others to be proliferative.