Detection of transcripts for β-actin in single Reed-Sternberg cells and their variants. Representative sampling of PCR results using primers specific for β-actin transcript. (A) Three randomly selected reamplified samples were titrated out to 1 : 100,000 dilution. (B) Each of the 49 reamplified single cell cDNA libraries was then diluted to 1 : 5,000 and screened for expression of β-actin. All single-cell libraries included in this study expressed β-actin titratable to at least 1 : 5,000. PCR products were run on ethidium bromide-stained 1% agarose gels. Positive or negative results were scored on the basis of intensity of ethidium bromide staining. Sample numbers correspond to cell numbers listed in Table 1. Molecular-weight markers (M) are labeled in base pairs.