Effect of cryopreservation on measurement of cytomegalovirus-specific cellular immune responses in HIV-infected patients

To determine the feasibility of cytomegalovirus (CMV)-specific cell-mediate d immunity (CMI) studies using cryopreserved cells, we compared lymphocyte proliferation assays (LPA), responder cell frequency (RCF), interleukin-2 ( IL-2) and interferon-gamma (IFN-gamma) production using fresh and cryoprese rved peripheral blood mononuclear cells (PBMCs) from 53 HIV-infected patien ts and 15 uninfected controls. Qualitative CMV LPA results were concordant in greater than or equal to 84% of the specimens from either HIV-infected p atients or controls. Proliferation-based RCF, IL-2, and IFN-gamma, comparis ons showed that cryopreservation reduces the number of CMV-specific respond ers and decreases cytokine secretion, without changing the rank order of th e results (p < .01). In contrast, the number of flow cytometry-enumerated I FN-<gamma>-producing CD4(+) cells was not significantly changed by cryopres ervation. In HIV-infected patients, the differences between fresh and froze n cell assays were not influenced by CD4 cell numbers or HIV viral load. Th ese data indicate that cryopreserved cells are suitable for longitudinal st udies of the CMV-specific immune response in HIV-infected patients and unin fected controls.