{'fraction_non_alphanumeric': 0.02042711234911792, 'fraction_numerical': 0.014856081708449397, 'mean_word_length': 5.533333333333333, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Specific Fractionation of Immunocompetent Cells

Prominent progress in molecular biology was only made when it became possible to separate functionally distinct molecules by taking advantage of their biophysical properties. Likewise, the analysis of the functions of heter ogeneous populations of immunocompetent cells, as to the functional properties of their various subpopulations, can not be done until these can be isolated in reasonably pure form by selective fractionation. During the last few years significant advances have been made in this field, and cells have been separated according to size, density or charge (Miller et al., 1969; Shortman, 1968; Andersson, 1973c), or by taking advantage of more specific surface markers to allow selective depletion or enrichment of a given subpopulation of cells (Wigzell and Andersson, 1971). Although separation techniques have been used in a variety of cellular systems, they have been particularly useful in the study of reticuloendothelial cells and primarily in the study of cells participating in the immune responses.