Polymorphonuclear cell functional impairment in relapsing remitting multiple sclerosis patients: preliminary data [G. Banche is the corresponding author]

Multiple Sclerosis patients run an increased risk of microbial infections, which leads to high rates of

hospitalization and infection-related mortality. Although immunotherapy may increase infection

risk in some cases, data as to the relationship among microbial factors, immunotherapy and

alterations in the innate immunity of these patients are still scanty. On these grounds, this

interdisciplinary study aims at investigating the role the functional activity of polymorphonuclear

cells (PMNs) play in relapsing remitting multiple sclerosis at different stages. The in vitro ability of

PMNs from patients, either untreated or treated with immunosuppressant or immunomodulatory

drugs to kill Klebsiella pneumoniae or Candida albicans, were investigated and compared to PMNs

from healthy subjects. The release of various cytokines was also assessed, as was the production of

reactive oxygen species and their ability to regulate apoptosis after microbial stimulation. Our

results indicate that although patients have a normal number of PMNs, they have a statistically

significant (p<0.05) reduction in intracellular killing activity. Although variations are strongly

related to the therapeutic management of patients, they are independent from their disease stage.

As no statistically significant differences were observed between patients and controls in cytokine

release values, reactive oxygen species production or apoptosis, we came to the conclusion that

other factors may be involved. Supportive validation of these results from further studies might well

help in identifying a subset of patients at high risk of infection who could benefit from a closer

follow-up and/or antibiotic prophylaxis.