Study of Pathogen-Specific Immune Responses and General Immune Competence in Opportunistic Infections

To better understand the relationship between immunologic responses, immune reconstitution, and the occurrence of OIs, observational data need to be collected (1) in patients who present with an OI before initiation of potent antiretroviral therapy, (2) in patients with a history of such OIs who have had secondary prophylaxis or maintenance therapy withdrawn and do not develop OI recurrence after potent antiretroviral therapy, and (3) in controls who were exposed to the pathogen of interest but never were at risk for disease because their immunity was not severely compromised. Immunologic comparisons may identify correlates of protection for a group of patients who do not develop an OI after potent antiretroviral therapy-induced immune reconstitution. Conversely, a subpopulation of patients may be identified that lacks critical host factors of protection and is more likely to develop an OI after immune reconstitution, and therefore would benefit from continued prophylaxis, regardless of CD4 cell count.

This study consists of 3 groups and 8 [AS PER AMENDMENT 4/17/01: 6] subgroups. Clinical microbiological data are collected and samples are obtained for immunologic assays (pathogen-specific and general) in all groups at entry (time of OI presentation for Group 1 patients) and at 12 weeks (except Group 3b). Group 1b patients also are evaluated at 24 weeks [AS PER AMENDMENT 4/17/01: The following text has been deleted: and at the time of diagnosis of immune-recovery vitreitis, if it should develop]. [AS PER AMENDMENT 4/17/01: Once patients in Groups 1, 2, and 3a have completed the Week 12 evaluations, they will be off-study.] Blood samples, 1 to 7 days apart, for peripheral blood mononuclear cells (PBMCs), LPA, and inducible cytokine expression of interferon gamma, interleukin-2, interleukin-4, and interleukin-10 are obtained.