BASIC TYPES AND VITAL FORMS OF HUMAN PERIPHERAL AND PHA-STIMULATED LYMPHOCYTES
REVEALED IN VITRO
S. Yu. Djomin
Institute of Cytology RAS, St. Petersburg
Natural diversity in peripheral and PHA-stimulated lymphocytes seen in the same donors was studied using
digitized streak photo of living cells in observational camera. Cells were monitored for 5-8 h at the superior
limit of optical resolution by means of phase-contrast microscopy. Intact lymphocytes were observed in autological
blood plasma, and PHA-stimulated lymphocytes were examined in self-conditioned centrifuged growth medium. The
majority of intact cells were small- and middle-sized floating lymphocytes with microvilli, and middle-sized
caudate lymphocytes capable of stick-slip motion. The lesser part consisted of "spread-eagle" or movable forms of
both large granular lymphocytes and middle-sized lymphocytes of several types: narrow-plasm lymphocytes with
lamellipodia, wide-plasm lymphocytes without cytoplasmic processes, lymphocytes with single pseudopodia, and
lymphocytes with single lobopodia of complex shape. On the contrary, the minor fraction of PHA-stimulated
lymphocytes of 3 day old cultures contained floating cells with microvilli or floating cells with microvilli and
two pseudopodia, whereas the majority of these lymphocytes were spread-eagle or movable forms of cells of
different type. These substrate-adhesive PHA-stimulated lymphocytes had well defined apical and basal cell
surfaces, but upon mechanical stress are easily pinched off to become ball-shaped. At least 6 different cell types
were distinguished among substrate-adhesive PHA-stimulated lymphocytes, with more than half of these being heavily
vacuolated spheroid lymphocytes prone to forming cell clusters. The rest PHA-stimulated lymphocytes were
represented by signet-ring lymphocytes with dark or light cytoplasm, narrow-plasm lymphocytes with large prolonged
nuclei and lamellipodia, lymphocytes with single lobopodia, and lymphocytes with single spiral structures in the
cytoplasm. The spiral structure is 10-11 μm in length and 0.5-0.7 μm in width, being presumably a
mitochondrion or a group of butt-joined mitochondria. Since some of the caudate middle-sized lymphocytes also
contain this structure, these may be regarded as putative precursors of respective type of PHA-stimulated
lymphocytes. Under the conditions of observation, interphase nuclei of all live PHA-stimulated lymphocytes were
seen to contain numerous globular or fiber structures of condensed chromatin made of 0.3-0.8 μm beads. These
beads are doubtless interphase chromomeres.
Key words: peripheral lymphocytes, PHA-stimulated lymphocytes, condensed chromatin
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