Induction of thymocyte apoptosis in mice by Yersinia enterocolitica products

In-vivo administration of the culture supernates from Yersinia enterocolitica resulted in thymus atrophy in C3H/HeJ mice, known to be lipopolysaccharide (LPS)-non-responders. The thymocytes underwent apoptosis as characterised by fragmented DNA ladders on agarose gel electrophoresis, a cell death detection ELISA and a morphological study by the TUNEL reaction. As a control, LPS treatment did not induce thymocyte apoptosis in C3H/HeJ mice. Flow cytometric analysis indicated that thymus atrophy was due predominantly to the deletion of CD4⁺CD8⁺ T cells. When cells were undergoing apoptosis, an elevation in the percentage of T-cell receptor (TCR)-αβ(high) cells was observed at 24 h, which was correlated with the increase in the percentages of cells expressing high levels of the Vβ6 and Vβ8 TCR. Gel electrophoretic analysis demonstrated the presence of protein bands with mol. wts ranging from 17 to 65 kDa in Y. enterocolitica culture supernates.