Longitudinal tracking of immune cell subsets and phenotypes in cynomolgus monkeys following immunization with two model antigens (P3369)

Abstract

Abstract Antigen immunization studies in cynomolgus monkeys (cyno) provide an opportunity to study in vivo immune responses in a higher order species. Such models can also be useful for testing candidate immunomodulatory drugs which lack rodent cross-reactivity. Here, we have optimized and validated eight, 6-7 color panels of cyno-human cross-reactive antibodies allowing extensive flow cytomtric phenotyping of immune cell populations under steady state, Tetatanus Toxoid (TT), or Keyhole limpet hemocyanin (KLH) primed conditions. Comparisons were made between fresh & overnight cells in Na/Hep tubes to cells phenotypically stabilized in Cytochex tubes. We followed 17 distinct lymphocyte subsets including T, B & NK cells and tracked their activation status over 85 days following primary or secondary immunization. Similar to humans, cyno B & T cell compartments demonstrated a history of prior stimulation evidenced by elevated memory:naive cell ratios and significant baseline expression of CD95, GrB, Ki-67, PD-1, CXCR3, CCR6 and CD11c. In response to immunization, frequencies of circulating Ki67+ B & T cells increased, followed by an elevation of T dependent Ab titers. Changes in Th1 and Th17 subset frequencies as well as CD25 and CD69 expression following immunization were also observed. Direct application of these Ab panels to leukocytes from Rheumatoid Arthritis patients has recapitulated published observations supporting the utility of modeling immune responses in cyno.