c("donor: 1", "cell type: M1 macrophages (classically activated)")
c("donor: 2", "cell type: M1 macrophages (classically activated)")
c("donor: 3", "cell type: M1 macrophages (classically activated)")
c("donor: 1", "cell type: M2 macrophages (alternatively activated)")
c("donor: 2", "cell type: M2 macrophages (alternatively activated)")
c("donor: 3", "cell type: M2 macrophages (alternatively activated)")