Expression of IL-10 mRNA was determined by real time PCR in purified splenic CD4+ T cells obtained on days 1, 3, 5 and 7 post-infection from wild type (WT) C57/BL6 mice and plasma levels of IL-10 were determined by ELISA on days 1, 3, 5 and 7 pi from WT and RAG−/− mice. Here, CD4 is linked to infection.