T lymphocytes: (A), ratio of CD4+/CD8+ T cells; (B), activation within the CD4+ and CD8+ T cell subsets. The result for T cell activation shows the percentage of HLA class II-expressing cells among all CD4+ T cells and CD8+ T cells, respectively. The indicated activation values are normalized with the result of the normal control individuals being expressed as 1.0, and the dashed lines indicate the level of the normal controls. Patient group codes: Gr-, septicaemia and/or pyelonephritis with gram-negative enterobacteria; EBV, Epstein-Barr virus; Inf, influenza; Tb, tuberculosis; Bo, neuroborreliosis; MCT, mixed connective tissue disorders; N, normal healthy controls. *p < 0.02 or 0.05, ** p < 0.01.