Glycosylation, the enzymatic attachment of glycans to biomolecules, is a vital post-translational modification that impacts protein stability, immune recognition, and cellular communication. Traditionally associated with proteins and lipids, recent discoveries have revealed the existence of glycosylated RNAs (glycoRNAs), expanding our understanding of RNA modifications. GlycoRNAs challenge conventional paradigms by suggesting that glycosylation may regulate RNA stability, localization, and interactions with glycan-binding proteins, such as sialic acid-binding immunoglobulin-type lectins (Siglecs) and selectins. These interactions are particularly significant in the immune system, where glycosylation plays a key role in antigen recognition, immune cell trafficking, and pathogen detection. The potential implications of glycoRNAs in immune regulation and disease are profound, with roles in autoimmune disorders, cancer, and infectious diseases. Advances in glycobiology, including mass spectrometry, RNA sequencing, glycan microarrays, and click chemistry technologies, are driving the growth of glycoRNA research and its translational applications. Understanding glycoRNAs could lead to new therapeutic opportunities, including glycoengineering, biomarker discovery, and targeted immune interventions. Despite challenges including low abundance and complex structure, research into glycoRNA is progressing rapidly, revealing their roles in immune responses and disease mechanisms. This review synthesizes the current knowledge on glycoRNAs, highlighting their emerging significance in immunology and outlining future research directions.

The amount of knowledge about new classes of small RNA molecules has expanded at a breathtaking pace in the last few years. This expansion is mainly due to the advent of new, advanced, technologies to profile RNAs, such as massively parallel signature sequencing (MPSS) and 454 pyrosequencing. Until recently, rare RNA species had only a small chance of being discovered because of the small-scale sequencing approaches used. The vast amounts of data presently generated and coupled with computational analysis allow a yet unprecedented exploration of the heterogeneity of 20- to 30-nt-long small RNAs and their role in post-transcriptional gene regulation. The continual discovery of new small RNA species suggests that we are only just beginning to appreciate the complexity of small RNAs and their functions. Extended studies on these new exciting classes of small RNAs, which were previously thought to be mere degradation products, will undoubtedly uncover novel roles for these tiny molecules in health and disease.

Transgenic expression of B- and T-cell receptors (BCRs and TCRs, respectively) has been a standard tool to study lymphocyte development and function in vivo. The generation of transgenic mice is time-consuming and, therefore, a faster method to study the biology of defined lymphocyte receptors in vivo would be highly welcome. Using 2A peptide-linked multicistronic retroviral vectors to transduce stem cells, TCRs can be expressed rapidly in mice of any background. We aimed at adopting this retrogenic technology to the in vivo expression of BCRs. Using a well characterised BCR specific for hen egg lysozyme (HEL), we achieved surface expression of the retrogenically encoded BCR in a Rag-deficient pro B-cell line in vitro. In vivo, retrogenic BCRs were detectable only intracellularly but not on the surface of B cells from wild type or Rag2-deficient mice. This data, together with the fact that no BCR retrogenic mouse model has been published in the 7 years since the method was originally published for TCRs, strongly suggests that achieving BCR-expression in vivo with retrogenic technology is highly challenging if not impossible.

Dendritic cells (DCs) are professional antigen-presenting cells that induce and regulate adaptive immunity by presenting antigens to T cells. Due to their coordinative role in adaptive immune responses, DCs have been used as cell-based therapeutic vaccination against cancer. The capacity of DCs to induce a therapeutic immune response can be enhanced by re-wiring of cellular signalling pathways with microRNAs (miRNAs).