Mast cells and eosinophils in allergic and eosinophilia diseases

Mini-review article

My mini-review of mast cells and eosinophils in allergic and eosinophilia diseases is now published.

Ricke DO. Mast cells and eosinophils in allergic and eosinophilia diseases. Explor Asthma Allergy. 2025;3:100983. https://doi.org/10.37349/eaa.2025.100983

Eosinophils are the “big gun” of the innate immune system for fighting multicellular parasites (e.g., infectious worms, etc.).

The path to this mini-review started with COVID-19 and evaluating candidate treatments early in 2020.

Malone RW, Tisdall P, Fremont-Smith P, Liu Y, Huang X-P, White KM, Miorin L, Moreno E, Alon A, Delaforge E, Hennecker CD, Wang G, Pottel J, Blair RV, Roy CJ, Smith N, Hall JM, Tomera KM, Shapiro G, Mittermaier A, Kruse AC, García-Sastre A, Roth BL, Glasspool-Malone J and Ricke DO (2021) COVID-19: Famotidine, Histamine, Mast Cells, and Mechanisms. Front. Pharmacol. 12:633680. doi: 10.3389/fphar.2021.633680

Trying to understand what was going on with Multisystem Inflammatory Syndrome in Children (MIS-C) provided new insights into understanding Kawasaki’s Disease, associated coronary artery aneurysms, COVID-19 myocarditis, COVID-19 pericarditis, and more.

Fremont-Smith, Maurice, et al. Models for COVID-19 Early Cardiac Pathology Following SARS-CoV-2 Infection. International Journal of Infectious Diseases, Volume 113, 331 - 335 doi: https://doi.org/10.1016/j.ijid.2021.09.052

Ricke DO, Gherlone N, Fremont-Smith P, Tisdall P, Fremont-Smith M. Kawasaki Disease, Multisystem Inflammatory Syndrome in Children: Antibody-Induced Mast Cell Activation Hypothesis. J Pediatrics & Pediatr Med. 2020; 4(2): 1-7 PDF

In many diseases dominated by eosinophils, the potential role of mast cells may be underappreciated. Some allergic diseases are caused by pollen, specific food allergies, etc. Triggering eosinophils can result in a variety of diseases. Eosinophils and mast cells attract each other when activated and can form cellular couplets and also positive activation loops (i.e., they don’t stop activating - cause ongoing disease symptoms).

Figure 1. Mast cells and eosinophils activation loop. Elevated histamine levels is hypothesized to possibly contribute to some forms of chronic heart disease where elevated histamine levels are inducing cardiac capillary pericyte cells to constrict resulting in vasoconstrictions, ischemia and anoxia of cardiac muscle cells.

We first observed these candidate vasoconstrictions in cardiac autopsy images of COVID-19 patients.

Figure 2. NIH COVID-19 Digital Pathology Repository putative COVID-19 patient heart H&E Tissue autopsy 73, image 1560 (40X) of capillary with red blood cells.

This is a free substack.