CD8A and X-linked agammaglobulinemia: Buggert and colleagues used CITE-Seq (cellular indexing of transcriptomes and epitopes by sequencing) and single-cell RNA-Seq to analyze the phenotype and transcriptome of CD8+ T cells from X-linked agammaglobulinemia (XLA) patients (lacking functional B cells) and healthy controls 35 days and 6 months after the initial vaccine dose.