Interleukin 5 immunotherapy depletes alloreactive plasma cells.

Area of Science:

• Immunology
• Transplantation Science
• Allergy and Asthma Research

Background:

• Long-lived plasma cells (PCs) produce donor-specific alloantibodies (DSAs), leading to positive crossmatches and transplant rejection.
• Current desensitization methods, like proteasome inhibitors, are effective but toxic.
• Eosinophils influence PC persistence, and Interleukin 5 (IL-5) depletion reduces eosinophils.

Purpose of the Study:

• To investigate if anti-IL-5 antibody treatment can deplete alloreactive PCs.
• To determine if anti-IL-5 therapy can reduce DSAs as a less toxic alternative to proteasome inhibition.
• To evaluate the safety and efficacy of IL-5 directed immunotherapy in a mouse model.

Main Methods:

• BALB/c mice were sensitized with B6 skin allografts.
• After 8 weeks, experimental mice received weekly anti-IL-5 antibody injections, while controls received phosphate-buffered saline.
• Plasma cells were quantified using enzyme-linked immunosorbent spot assay.

Main Results:

• All mice developed positive crossmatches.
• Anti-IL-5 treated mice showed a reduction in total PC numbers.
• Experimental mice exhibited negligible weight loss and lymphopenia, unlike proteasome inhibition.

Conclusions:

• Anti-IL-5 treatment reduces, but does not eliminate, alloreactive PCs by targeting eosinophils and associated survival factors.
• This immunotherapy demonstrates reduced generalized toxicity.
• IL-5 directed therapy is unlikely to be a clinically significant desensitization strategy due to persistent DSAs.