Figure 6.

Decrease in the proportion of CD27⁺ B memory cells in co-culture with preconditioned CD4⁺ T memory (Tm) cells. (a) Various numbers of fresh or preconditioned CD4⁺ Tm were cultured with carboxyfluorescein diacetate succinimidyl ester (CFSE)-unlabelled or CFSE-labelled B cells in the presence of pokeweed mitogen (PWM) for 4–7 days. Cells from culture containing CFSE-unlabelled B cells were harvested at day 7, stained with anti-CD4-fluorescein isothiocyanate (FITC), anti-CD27-phycoerythrin (PE) and anti-CD19-allophycocyanin monoclonal antibodies (mAbs) and analysed for the proportion of total B cells (defined as CD19^+/– CD4^– events) or for the proportion of CD27⁺ B cells (defined as CD19^+/– CD27⁺ CD4^– events). Data are from one representative experiment of three. Cells from co-culture and transwell assay containing CFSE-labelled B cells were harvested at day 4, stained with anti-CD27-PE mAb and analysed by flow cytometry. Dot plots display CD27 expression as a function of division of CFSE-labelled B cells with the percentages of CD27⁺ B cells indicated in each dot plot (dashed line shows staining with control mAb). Undivided CFSE-labelled B cells are indicated in each dot plot (numbers in boxes). Data are from events above dashed line; one representative experiment of four. (b) Fresh or preconditioned CD4⁺ Tm cells were cultured with ⁵¹Cr-labelled PWM-stimulated B cells (3 × 10⁴) at effector:target ratios of 0·5 : 1 to 5 : 1 for 13 hr, at which time supernatants were collected and analysed for ⁵¹Cr release. The data are displayed as the mean ± standard error of the mean (SEM) for triplicate measurements and are representative of three separate experiments. Mo, monocytes.