In the group with past EBV infection (Figure 2C), the IgG level correlated negatively with the CD4(+) T lymphocyte (r: −0.3256; p < 0.0001) and double-positive T lymphocyte (r: −0.1108; p: 0.0401) counts and positively with the CD8(+) T lymphocyte count (r: 0.1712; p: 0.0016). Here, CD4 is linked to Epstein-Barr virus infection.