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Exosomes are released by cells as self-contained vesicles with an intact lipid bilayer that encapsulates a small portion of the parent cell. Exosomes have been studied widely as information-rich sources of potential biomarkers that can reveal cellular physiology. We suggest that quantification is essential to understand basic biological relationships between exosomes and their parent cells and hence the underlying interpretation of exosome signals. The number of methods for quantifying exosomes has expanded as interest in exosomes has increased. However, a consensus on proper quantification has not developed, making each study difficult to compare to another. Overcoming this ad hoc approach will require widely available standards that have been adequately characterized, and multiple comparative studies across platforms. We outline the current status of these technical approaches and our view of how they can become more coherent.

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Background Hodgkin Lymphoma (HL) is uncommon in the U.S. general population; however, HL risk is elevated in people with human immunodeficiency virus (HIV) infection. Thus, despite the low HIV prevalence in the U.S, the HIV epidemic may have contributed substantially to the general population burden of HL. Methods We used data from 14 U.S. cancer registries in the Surveillance, Epidemiology and End Results Program that recorded HIV status of HL cases at diagnosis during 2000–2010. We computed the HIV prevalence in HL cases by demographic and tumor characteristics, the proportion of deaths among HL cases due to HIV, and 5-year mortality by HIV status. Results Of 22,355 HL cases, 848 (3.79%) were HIV-infected at diagnosis. HIV prevalence in HL cases was greater among males than females (6.0 vs. 1.2%). Among males, HIV prevalence was greatest among 40–59 year-olds (14.2%), non-Hispanic blacks (16.9%), Hispanics (9.9%) and among cases of lymphocyte-depleted (15.1%) and mixed cellularity HL (10.5%). Eight percent of male and 1.5% of female HL cases died from HIV. Five-year mortality was two-fold higher in HIV-infected HL cases (36.9 vs. 17.5%). Conclusions In the U.S., a substantial proportion of lymphocyte-depleted and mixed cellularity HL cases and HL cases among non-Hispanic black, Hispanic and middle-aged men are HIV-infected. Additionally, HIV is an important cause of death among HL cases. Impact Clinicians should be aware of the high prevalence of HIV in certain subgroups of HL patients and routine HIV testing should be recommended for all patients presenting with HL.