Preface: Immune Biomarkers from Liquid Biopsies.

Liquid biopsies have gained importance in recent years due to their relative ease of obtaining, non-invasiveness or minimal invasiveness, and accurate response in detecting the emergence of several types of diseases, including infectious diseases, inflammation, or cancer. Liquid biopsies can be obtained from body fluids such as blood, plasma, saliva, urine, or other body liquids. This material detects proteins, mainly cytokines, circulating cell-free DNA, microRNAs, long non-coding RNAs, and mRNAs. In addition, liquid biopsies can be used to profile the transcriptome or proteome, evaluate exosomes, and even quantify peptides and other molecules that are expressed/secreted by the host in response to infectious diseases, inflammation, and cancer or autoimmune diseases, which might be used as non-invasive or minimally invasive disease biomarkers. This special issue offers a critical reading of the present research on liquid biopsies, given the current knowledge of molecular biology, applied to laboratory diagnostic assays.