CD8A and infection: Moreover, the frequency of both T helper CD4+ (TH) and cytotoxic T CD8+ (CTL) lymphocytes was different in VOCP breakthrough infections, with TH less represented in VOCP infections (36% vs. 52%, p = 0.055 and 54%, p = 0.045) and CTL more represented (VOCP median 50%) than in the other two groups (both VOCD and VOCO median = 35%, p = 0.038).