Abstract
To the Editor—We read with interest the recent article by Hsieh et al. [1] with regard to the potential clinical utility of measuring cytomegalovirus (CMV)–specific frequency of CD69 expression on CD4+ T cells in patients with AIDS who are at risk for CMV retinitis. The authors reported that the percentage of CD69+CD4+ T lymphocytes (after peripheral blood mononuclear cell incubation for 24 h with CMV antigen) was significantly lower in patients with active CMV retinitis than in similar patients with very advanced human immunodeficiency virus (HIV) disease who did not have CMV retinitis (median, 0.4% vs. 2.25%; P<.001). During a median 14.5 months of follow-up, none of 32 patients with a baseline CD69+ cell percentage of CMV on CD4+ T cells of >0.5% developed CMV retinitis, whereas 3 of 4 patients with a baseline percentage <0.5% did develop CMV retinitis
These results were of particular interest to us because we had previously published results of a study of the potential clinical utility of 2 different measures of CMV-specific CD4+ T lymphocyte functional responses in patients with CMV retinitis [2]. In our study, we examined the correlation of the results of a CMV-specific lymphocyte proliferation (LP) assay and of a CMV-specific Th1-type cytokine flow cytometric (CFC) assay (quantifying the percentage of CD4+ T cells expressing tumor necrosis factor–α or interferon-γ after CMV stimulation) with clinical evidence of CMV-protective immunity. Two groups of patients with AIDS with CMV retinitis were studied longitudinally: individuals with active retinitis whose absolute CD4+ count did not increase during follow-up (group 1a) and individuals who, immunorestored by highly active antiretroviral therapy (HAART), were able to discontinue anti-CMV treatment and remain without this treatment for at least 6 months without retinitis reactivation, as evidenced by serial ophthalmologic examination or subsequent decrease in CD4+ lymphocyte count (group 2a). Our results indicated that neither the CMV-specific LP nor the CMV-specific CFC assays were consistently positive in patients with intact CMV-protective immunity nor consistently negative in patients clinically lacking CMV-protective immunity. Thus, neither assay would have potential clinical utility in monitoring patients with CMV retinitis for risk of retinitis reactivation