Transiently boosting Vγ9+Vδ2+ γδ T cells early in Mtb coinfection of SIV-infected juvenile macaques does not improve Mtb host resistance.

Children living with HIV have a higher risk of developing tuberculosis (TB), a disease caused by the bacterium Mycobacterium tuberculosis (Mtb). Gamma delta (γδ) T cells in the context of HIV/Mtb coinfection have been understudied in children, despite in vitro evidence suggesting γδ T cells assist with Mtb control. We investigated whether boosting a specific subset of γδ T cells, phosphoantigen-reactive Vγ9+Vδ2+ cells, could improve TB outcome using a nonhuman primate model of pediatric HIV/Mtb coinfection. Juvenile Mauritian cynomolgus macaques (MCM), equivalent to 4-8-year-old children, were infected intravenously (i.v.) with SIV. After 6 months, MCM were coinfected with a low dose of Mtb and then randomized to receive zoledronate (ZOL), a drug that increases phosphoantigen levels, (n=5; i.v.) at 3- and 17- days after Mtb accompanied by recombinant human IL-2 (s.c.) for 5 days following each ZOL injection. A similarly coinfected MCM group (n=5) was injected with saline as a control. Vγ9+Vδ2+ γδ T cell frequencies spiked in the blood, but not airways, of ZOL+IL-2-treated MCM following the first dose, however, were refractory to the second dose. At necropsy eight weeks after Mtb, ZOL+IL-2 treatment did not reduce pathology or bacterial burden. γδ T cell subset frequencies in granulomas did not differ between treatment groups. These data show that transiently boosting peripheral γδ T cells with ZOL+IL-2 soon after Mtb coinfection of SIV-infected MCM did not improve Mtb host defense.
Competing Interests: Conflicts of Interest: L.C.N. reports grants from the NIH and has received consulting fees from work as a scientific advisor for AbbVie, ViiV Healthcare, and Cytodyn where he also serves on the Board of Directors for work outside of the submitted work. D.I.G. is an inventor on two patents related to human Vγ9Vδ2 T cell stimulation. All other authors declare that they have no conflict of interest.