OMIPs start school.

Abstract

It's now exactly 6 years ago, that in September 2010 the concept, guidelines, and the first OMIPs were launched. The initiator of the OMIP was Mario Roederer, NIH Bethesda, who also provided the two first OMIPs that served as trial balloons for testing whether enough input can be generated from different research groups who were developing and performing polychromatic flow cytometry. Initially it was unclear how sustainable the OMIP manuscript format will be. It took over a year until the next OMIP was published and critical voices said that the format will fade away soon. But now as OMIPs enter school age it turns out there is an ever growing community who provides their cutting edge developments on multiplexed single cell analysis. This month we publish OMIP number 35 (Weisgrau et al., this issue, page 799), meaning that on average six OMIPs per year are published and regarded by the scientific community as a work of research on its own value. Whereas the majority of OMIPs focus on human and murine leukocytes there are also several developed for other mammalian species. OMIP-035 in this issue by Weisgrau and colleagues scrutinizes the Natural Killer cell subsets in Macaque monkeys, continuing their work on NK cells in this species 1. Other Macaque OMIPs were already published in past years, on T cells and immune response with the most recent one on B cells in 2015 2. Are we now reaching an end of the OMIP publications? It does not seem so. On the one hand, flow cytometers equipped with a battery on new lasers 3 allow for optimal dye excitations and introduction of new dyes. Custom-designed instruments can analyze 25+ colors as presented at the last CYTO conferences and commercial research instruments can already measure up to 18 colors. OMIPs at this high level of complexity have not even been touched yet. The new way of spectral flow cytometry 4 may even go beyond that level and it's foreseeable that it will lead to new alternative panels wherein dyes with similar colors but different emission spectra are used simultaneously. Not to speak of the opportunities offered by mass cytometry. Here the first OMIP has just recently been accepted 5 and is already accessible. We expect more to come from this technology. And finally, so far most OMIPs put their focus on leukocyte phenotype and function. Only very few were dealing with other cell types (hematopoietic cells, circulating endothelial cells). But there are far more cell systems that take advantage of multiplexed analysis such as stem and progenitor cell or cancer cells and I welcome submissions on them. Graft-versus-host-disease (GvHD) is a feared, often lethal complication following hematopoietic stem cell transplantation. Schmidt et al. demonstrated last year in a mouse model that GvHD of transplanted murine T-helper cells can be prevented by administration of anti-human CD4 monoclonal antibodies 6. As mice can lie, the authors (Hilger et al., this issue, page 803) expanded their experiments by transplanting human leukocytes into another mouse model. Here they could clearly show that the anti CD4 antibody administration attenuates GvHD by reducing the number of circulating T helper cells. The Editor's Choice article of the month is a work from the group around Busch and colleagues (this issue, page 816). This group developed the innovative Streptamer technology that allows rapid isolation of even very rare cells using ligands or antibodies with low binding affinity and followed by stripping of the detecting molecules for the further use of the cells in cell therapy 7. In their present work, the authors expand the application of Streptamers for the kinetic measurement of the avidity of antigen recognition by the MHCI complex. This assay is versatile. It can be done by flow cytometry and imaging and allows the isolation of the most potential cells for further adoptive therapy. I hope you enjoy these highlighted and the other, not discussed, but none-the less highly interesting articles of this issue.