Effect of absolute CD4⁺ counts on CD4⁺ Th function (CMV and PHA) and CD8 counts on CMV-specific CD8⁺ CTL response. Patients with a CD4 cell count of at least 100 × 10⁹/L had significantly higher likelihood of demonstrating a positive CMV-specific Th response than those with a count less than 100 × 10⁹/L (P = .0006). There was no difference in CTL response between those who had a CD8⁺ count of at least 100 × 10⁹/L versus those with a CD8⁺ count less than 100 × 10⁹/L (P = .24); however, those with a CD8⁺ count of at least 50 × 10⁹/L had a significantly higher likelihood of demonstrating a positive response versus those with a CD8⁺ count less than 50 × 10⁹/L (P = .04).