Studies of CD40L expression by lymphoid cells from experimentally and naturally SIV-infected nonhuman primate species

Dysfunction of T lymphocytes is well documented in HIV-1-infected individua ls; however, the mechanisms responsible for the noted dysfunction are not w ell understood. CD40L is an important costimulatory molecule that helps ini tiate immune responses, and there is con troversy regarding whether or not expression of CD40L is compromised in HIV-1-infected individuals. We have u tilized the SIV infection of experimentally infected (disease-susceptible) and naturally infected (disease-resistant) nonhuman primates as animal mode ls of human AIDS to address this issue. Little is known concerning the expr ession of CD40L. in nonhuman primates. Studies were conducted to determine the frequency, density, phenotype, and kinetics of CD40L expression by in v itro activated peripheral blood mononuclear cells (PBMCs) from different sp ecies of uninfected and SIV-infected monkeys. Data obtained show marked dif ferences in the density and phenotypic lineage that expresses CD40L in lymp hoid cells from the three species examined. However, no detectable differen ces were noted in the frequency and density of CD40L expression by in vitro activated lymphoid cells from uninfected and SIV-infected disease-suscepti ble rhesus macaques and seropositive as compared to seronegative disease-re sistant sooty mangabeys. These data suggest that phenotypic expression of C D40L is not compromised due to SIV infection.