Preservation of lymphocyte immunophenotype and proliferative responses in cryopreserved peripheral blood mononuclear cells from human immunodeficiency virus type 1-infected donors: Implications for multicenter clinical trials

Human immunodeficiency virus type 1 (HTV-1) infection results in impaired i mmune function that can be measured by changes in immunophenotypically defi ned lymphocyte subsets and other in vitro functional assays. These in vitro assays may also serve as early indicators of efficacy when new therapeutic strategies for HIV-1 infection are being evaluated. However, the use of in vitro assays of immune function In multicenter clinical trials has been hi ndered by their need to be performed on fresh specimens. We assessed the fe asibility of using cryopreserved peripheral blood mononuclear cells (PBMC) for lymphocyte immunophenotyping and for lymphocyte proliferation at nine l aboratories. In HIV-1-infected patients with moderate CD4(+) lymphocyte los s, the procedures of density gradient isolation, cryopreservation, and thaw ing of PBMC resulted in significant loss of CD19(+) B cells but no measurab le loss of total T cells or CD4(+) or CD8(+) T cells, No significant change s were seen in CD28(-) CD95(+) lymphocytes after cell isolation and cryopre servation. However, small decreases in HLA-DR+ CD38(+) lymphocytes and of C D45RA(+) CD62L(+) were observed within both the CD4(+) and CD8(+) subsets. Fewer than 10% of those specimens that showed positive PBMC proliferative r esponses to mitogens or microbial antigens lost their responsiveness after cryopreservation. These results support the feasibility of cryopreserving P BMC for immunophenotyping and functional testing in multicenter AIDS clinic al trials. However, small changes in selected lymphocyte subsets that may o ccur after PBMC isolation and cryopreservation will need to be assessed and considered in the design of each clinical trial.