Search

Safe use of immune checkpoint blockade in patients with cancer and autoimmune disorders requires a better understanding of the pathophysiology of immunologic activation. We describe the immune correlates of reactivation of granulomatosis with polyangiitis (GPA)—an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis—in a patient with metastatic urothelial carcinoma treated with pembrolizumab. After PD-1 blockade, an inflammatory pulmonary nodule demonstrated a granulomatous, CD4+ T-cell infiltrate, correlating with increased CD4+ and CD8+ naïve memory cells in the peripheral blood without changes in other immune checkpoint receptors. Placed within the context of the existing literature on GPA and disease control, our findings suggest a key role for PD-1 in GPA self-tolerance and that selective strategies for immunotherapy may be needed in patients with certain autoimmune disorders. We further summarize the current literature regarding reactivation of autoimmune disorders in patients undergoing immune checkpoint blockade, as well as potential immunosuppressive strategies to minimize the risks of further vasculitic reactivation upon rechallenge with anti-PD-1 blockade. Key Points Nonspecific imaging findings in patients with cancer and rheumatological disorders may require biopsy to distinguish underlying pathology. Patients with rheumatologic disorders have increased risk of reactivation with PD-(L)1 immune checkpoint blockade, requiring assessment of disease status before starting treatment. Further study is needed to evaluate the efficacy of treatment regimens in preventing and controlling disease reactivation.

Peripheral blood mononuclear cells (PBMCs) are essential to the study of autoimmune, infectious, parasitic diseases, and cancer. In the rapidly growing field of cancer immunology, cellular phenotyping provides critical information about patient responses to treatments and treatment efficacies. Notably, the evaluation of T cell based therapies relies on the isolation of highly viable CD3+ T cell, CD4+ Helper T cell, and CD8+ Cytotoxic T cell populations before and during patient treatments. Cryopreservation of PBMC populations allows researchers to thaw and characterize clinical samples by flow cytometry, mass cytometry, sequencing, etc. in a high-throughput manner and in batches. Therefore, it is important to separate and bank an abundance of robust circulating immune cells. Here, we report our internal protocols for the high-quality separation, banking, and thawing of clinically relevant PBMC populations. We present quality control data from 11 melanoma patients and characterize their CD3+, CD4+, and CD8+ T cells by 4-color flow cytometry.