The TBE peripheral blood lymphocyte population contained 68 % of T CD3+ cells (890/μl), including 33 % of CD4+ (519/μl) and 24 % of CD8+ lymphocytes (334/μl) and 16 % of B cells (225/μl) and 13 % of NK cells (178/μl) on admission. The gene discussed is CD4; the disease is tick-borne encephalitis.