IL13 and infection: Although a decline in cytokine concentration was observed by 4 hours post Δ-mce1 H37Rv-infection, the lack of effect on transcription of the IL-13-inducible genes by 4 hrs post Δ-mce1 H37Rv-infection may be explained by a down-regulation of the IL-13 receptor by 4 hrs post Δ-mce1 H37Rv-infection.