Elimination of allogeneic donor cells in the absence of CD4⁺ cells.

To test if optimal recipient CD8⁺ and B-cell responses required help from CD4⁺ cells, C57BL/6 and DBA/2 mice were injected with anti-CD4 on days −3 and −2. Then on day 0 these mice were either used as source of donor cells or as recipients. Detectable levels of anti-CD4 could be maintained in the recipient mice for at least 10 days with this protocol. The CD4⁻donor splenocytes were labeled with FITC and then injected into the recipients which had also been injected with anti-CD4. Persistence of donor cells was measured in the spleen (shown) and lymph nodes on days 3, 5, 6, and 7 (mean of 3 mice per time point for DBA/2 into DBA/2 [□] and C57BL/6 into DBA/2 [◊] combinations and a mean of 2 mice per time point for the DBA/2 into C57BL/6 [○] combinations are shown).