The development of an adoptive transfer model to evaluate <i>Mtb</i>-specific CD4 T cells.

<p>(A) Donor mice (B6.SJL, CD45.1) injected with BCG 2 mo before were boosted with Ag85B-TB10.4 and killed 7 days later. Spleen and lymph nodes were removed, depleted of B cells, CD8 T cells and macrophages. A representative profile of the resulting CD4 T cell population stained for CD45RB is shown (B). CD4 T cells were also depleted of CD45RB^high cells and injected into recipients on day 0 (d 0). A representative profile of CD45RB^low CD4 T cells used for adoptive transfer is shown (C). One day after transfer, irradiated recipients (X-rad) were challenged i.v. with live BCG, killed 3 weeks later (d 22) and spleens tested for a reduction in BCG numbers (Protection assay, CFUs/spleen). An aliquot of spleen cells was cultured overnight in the presence of Ag85B-TB10.4 antigen and stained for ICC IFN-γ. Donor-derived CD4 T cells (CD4⁺ CD45.1⁺) were gated in R1 (D) and analysed for IFN-γ positive cells (E). The donor-derived CD45.1⁺ CD4⁻ cells in profile D (upper left quadrant) were predominantly contaminating B cells. Numbers in the representative profiles are the percentage of events in the quadrant.