Table 1.

Trypanosoma cruzi infects mouse thymic epithelial cells (TECs)^*, affecting TEC replication and adhesion of thymocytes.

	Non-infected	Infected	p-value
Thymic epitelial cell numbers**
Total TEC numbers	7.00 ± 0.63	3.20 ± 0.33	p < 0.02
BrdU+ TEC numbers	56 ± 1.10	14 ± 0.40	p < 0.02
Association index applied to quantify thymocyte adhesion to TECs***	33.6 ± 2.5	80.0 ± 4.4	p < 0.05
	TEC/Tc(–)	TEC/Tc(+)
	67 ± 0.9	200 ± 21.5	p < 0.05

^*The TEC line IT-76M1 was originally developed from a primary culture of BALB/c thymic stromal cells and was kindly provided by Dr. T. Itoh (Tohuku University Medical School, Sendai, Japan). TEC cultures were allowed to adhere to culture flasks (1 × 10⁵ cells) and were infected with T. cruzi 24 h later, being then washed extensively. Trypomastigote forms of the Colombian strain were applied to infect TEC cultures. After 6 h, free parasites were discarded by repeated washings, and the TEC cultures were maintained for further 48 h.

^**The numbers of cultured TECs were ascertained by directly counting single-cell suspensions after detaching the cells Additionally, the proliferative status of the infected and uninfected TEC cultures was analyzed using a BrdU incorporation assay (30 min at 37°C). The presence and counting of BrdU⁺ cells were determined by fluorescence microscopy.

^***Infected or non-infected TEC cultures were maintained for 48 h, being then incubated with 5 × 10⁶ thymocytes, obtained by the mechanical disruption of control thymuses, in serum-free RPMI medium for 30 min at 37°C. Floating, non-adherent thymocytes were removed and the plates were fixed in methanol and stained with Giemsa solution. The number of adhered thymocytes per at least 1,000 TECs were directly counted, and the association index (AI) was calculated as follows:

AI, TECs with bound thymocytes × thymocytes bound to TECs × 100

total TEC number total TEC number

All data showed in this table were retrieved from Farias-de-Oliveira et al. (48).