Long-term CD40-stimulated B cells remain EBV-free.

<p>(<i>A</i>) PCR was used to detect the EBV EBNA1 gene in CD40-stimulated B cells from eleven donors after various culture periods (the number of days is indicated in parentheses for each cell line). EBV DNA and EBV-infected B lymphoblastoid cell lines GXLK and LXB2 were used as positive controls. (<i>B</i>) The PCR protocol allowed the detection of one EBV-infected cell equivalent per reaction. (<i>C</i>) In this example of a routine PCR analysis of early-passage CD40-stimulated B cell cultures, EBV was detected in one of 17 cultures from three different EBV-positive donors. B cell cultures had been set up with 100,000 PBMC each and were tested on day 80–90 of culture.