We observed a trend toward lower counts of CD4+ T cells (mean: 104 cells/μl; range: 30–611, p = 0.0577) and of naïve CD4+ T cells (mean: 5 cells/μl; range 1.69–8.5, p = 0.0991) in vasculitis patients than in the non-vasculitis group (CD4+ T cells, mean: 257 cells/μl; range 66–958; naïve CD4+ T cells, mean: 7 cells/μl; range 0.04–47), although this did not reach significance. Here, CD4 is linked to vasculitis.