Morphological analysis of the cellular interaction between thymocytes and a thymic stromal cell line (TEL‐2)

Abstract

In a previous study (Nakashima et al., Eur. J. Immunol., 20: 47-53, 1990), a cloned stromal cell line TEL-2 was established from Balb/c mouse thymus. Incubation of thymocytes with TEL-2 cells resulted in the selective elimination of CD4 and CD8 double-positive thymocytes from the culture. In the present report, both phase-contrast and scanning electron microscopes were used to examine, at various time intervals, TEL-2 cells cocultivated with thymocytes in order to elucidate the kinetic sequence of their cellular interaction. The thymocytes attached to the TEL-2 cell surface were more numerous at early times (30 min to 1 h), and their number decreased gradually with time. In contrast, the thymocytes that migrated into the TEL-2 cell layers were less abundant at early times, their number increasing with time thereafter. Destruction of the regular arrangement of TEL-2 cells was found at later than 1 h, suggesting active cellular interaction. The thymocytes adherent to the TEL-2 cell surface were found to be of various shapes and often showed variable profiles, e.g., extending small cytoplasmic processes along the surface of TEL-2 cells or appearing ameboidal. A remarkable feature of the TEL-2 cells was that they formed numerous "round spaces" at the surface of the TEL-2 cell layers. The thymocytes were often located around "round spaces," and some were seen migrating into TEL-2 cell layers through these round spaces. In addition, complementary examinations by transmission electron microscopy revealed that the internalization of thymocytes into TEL-2 cells occurs inside the TEL-2 cell layers after migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Different Roles of a Rat Cortical Thymic Epithelial Cell Line In Vitro on Thymocytes and Thymocyte Hybridoma Cells: Phagocytosis, Induction of Apoptosis, Nursing and Growth Promoting Activities

“…The nursing activity of the R-TNC.1 cell line was manifested by the engulfment (emperiopolesis) of thymocytes after their binding to TEC (Č olić et al, 1994). The characteristics of the line appear to be identical with TNC reported by Wekerle et al (1980), and mouse stromal cell lines which formed characteristics complex structures with thymocytes in the monolayers and hanging drop culture system (Itoh et al, 1988;Nishimura et al, 1990;Hiramine et al, 1990;Hirata et al, 1991;Li et al, 1992). To our knowledge this is the first line with nursing characteristics established from the rat thymus.…”

“…However, binding of TH cells was stronger in comparison to thymocytes. Hirata et al (1991) also found that the number of thymocytes adhering to the mouse TEL-2 line with nursing activity was greatest at 1 h, followed by their significant detachment after prolonged cocultivation. We have previously demonstrated that LFA-1 and its ligand ICAM-1 are partly involved in the binding of thymocytes to both cortical, R-TNC.1 and medullary (TE-R2.5) cell lines in the early adhesion phase (30 min) (Č olić et al, 1994; 1997).…”

Morphological study of thymus stromal cells (TEL-2 cell) which play a role in the elimination of double positive immature thymocytes by phagocytosis

“…7d), followed the ingestion of thymocytes by TEL-2 cells. The ultrastructure of these binding sites may suggest the presence of specific receptors for cellular recognition between thymocytes and thymus stromal cells (TEL-2 cells) (LaRochelle and Jones, 1989;Hirata et al, 1991).…”

“…Thus, TEL-2 cells are considered to play a role in the disappearance of DP thymocytes. In a follow-up study with SEM and transmission electron microscopy (TEM), Hirata et al (1991) have shown that as an initial event for the process of the selective elimination of DP thymocytes from the culture, the attachment between the thymocyte and TEL-2 cell leads to a migration of thymocytes between the TEL-2 processes. Similar cellular interactions between thymocytes and thymic stromal elements have been described in vitro (LaRochelle and Jones, 1989).…”