Classification clumping

Initial classification of some cytokines was also undertaken on the basis of the specific biological activity by which the cytokine was first discovered (e.g. TNF exhibited cytotoxic effects on some cancer cell lines CSFs promoted the growth in vitro of various leukocytes in clumps or colonies). This, too, proved an unsatisfactory classification mechanism, as it was subsequently shown that most cytokines display a range of biological activities (e.g. the major biological function of TNF is believed to be as a regulator of both the immune and inflammatory response). More recently, primary sequence analysis of cytokines coupled to determination of secondary and tertiary structure reveal that most cytokines can be grouped into one of six families (Table 8.2). 

We should, however, always be aware of situations in which microscopists are better than cytometrists—certain types of classification are easy by eye but not at all easy by cytometer. For example, a microscopist would never confuse a dead lymphocyte with an erythrocyte, nor a chunk of debris with a viable cell such mistakes are all too frequent in cytometry. Furthermore, microscopists, if they were not so polite, would find it laughable that cytometrists have a great deal of difficulty in distinguishing clumps of small cells from single large cells. However, if we think back to the discussion in Chapter 3 about the origin of the FSC signal, we can see why these problems occur and why we need to be aware of the limits of flow cytometry (and why a microscope is an essential piece of equipment in a flow cytometry lab). 

More simply Pichon et al. [149] detected the core of S. ambofaciens et P. roqueforti pellets by series of openings. The hairiness of annular zones, as well as the own of clumps was characterized by a complexity index based on the number of holes and the perimeter of the pellet and its holes. The openings approach was also used by Tamura et al. [106] for pellet core detection, but their classification between filament and clumps is based on A/P2. The classification of S. virginiae morphology by Yang et al. [150] into three classes relies exclusively on the Oval Major Axis (OMA) defined by ... 

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