Cell and Tissue Staining Kit

Microglial cells are the main reservoir for HIV-1 within the brain and potential exists for negative immune checkpoint blockade therapies to purge this viral reservoir. Here, we investigated cytolytic responses of CD8(+) T lymphocytes against microglia loaded with peptide epitopes. Initially, flow cytometric analysis demonstrated efficient killing of HIV-1 p24 AI9 or YI9 peptide-loaded splenocytes in MHC-matched recipients. Cytolytic killing of microglia was first demonstrated using ovalbumin (OVA) as a model antigen for in vitro cytotoxic T lymphocyte (CTL) assays. Peptide-loaded primary microglia obtained from programmed death ligand (PD-L) 1 knockout (KO) animals showed significantly more killing than cells from wild-type (WT) animals when co-cultured with activated CD8(+) T-cells isolated from rAd5-OVA primed animals. Moreover, when peptide loaded-microglial cells from WT animals were treated with neutralizing alpha-PD-L1 Ab, significantly more killing was observed compared to either untreated or IgG isotype-treated cells. Most importantly, significantly increased in vivo killing of HIV-1 p24 YI9 peptide-loaded microglia from PD-L1 KO animals, as well as AI9 peptide-loaded BALB/c microglial cells treated with alpha-PD-L1, was observed within brains of rAd5-p24 primed-CNS boosted C57BL/6 or BALB/c mice, respectively. Finally, ex vivo responses of brain CD8(+) T-cells in response to AI9 stimulation showed significantly increased IFN-gamma and IL-2 production when treated with alpha-PD-1 Abs. Greater proliferation of CD8+ T-cells from the brain was also observed following blockade. Taken together, these studies demonstrate that PD-L1 induction on microglia restrains CTL responses and indicate that immune checkpoint blockade targeting this pathway may be beneficial in clearing viral brain reservoirs.

PURPOSEThis Provisional Clinical Opinion update presents a clinically pragmatic approach to hepatitis B virus (HBV) screening and management.PROVISIONAL CLINICAL OPINIONAll patients anticipating systemic anticancer therapy should be tested for HBV by 3 tests-hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc) total immunoglobulin (Ig) or IgG, and antibody to hepatitis B surface antigen-but anticancer therapy should not be delayed. Findings of chronic HBV (HBsAg-positive) or past HBV (HBsAg-negative and anti-HBc-positive) infection require HBV reactivation risk assessment.Patients with chronic HBV receiving any systemic anticancer therapy should receive antiviral prophylactic therapy through and for minimum 12 months following anticancer therapy. Hormonal therapy alone should not pose a substantial risk of HBV reactivation in patients with chronic HBV receiving hormonal therapy alone; these patients may follow noncancer HBV monitoring and treatment guidance. Coordination of care with a clinician experienced in HBV management is recommended for patients with chronic HBV to determine HBV monitoring and long-term antiviral therapy after completion of anticancer therapy.Patients with past HBV infection undergoing anticancer therapies associated with a high risk of HBV reactivation, such as anti-CD20 monoclonal antibodies or stem-cell transplantation, should receive antiviral prophylaxis during and for minimum 12 months after anticancer therapy completion, with individualized management thereafter. Careful monitoring may be an alternative if patients and providers can adhere to frequent, consistent follow-up so antiviral therapy may begin at the earliest sign of reactivation. Patients with past HBV undergoing other systemic anticancer therapies not clearly associated with a high risk of HBV reactivation should be monitored with HBsAg and alanine aminotransferase during cancer treatment; antiviral therapy should commence if HBV reactivation occurs.Additional information is available at www.asco.org/supportive-care-guidelines.