For cat lovers, the most tragic thing is probably the cat allergy. As soon as you get close to the cat, you sneeze, have a runny nose, or itchy eyes, skin rashes, and even asthma attacks.

There are many people who are allergic to cats, with about 1 in 10 in the population. In some areas, as many as 30% of the population are allergic to cats.

While enduring allergies, there are many cat slaves who insist on keeping cats. However, there are also some people who have to send their cats away due to severe allergies of themselves or their family members. Either way is painful.

Many people think cat hair is the culprit, but it is not. The real allergen is mainly a protein called Fel d 1 that is secreted through cat's saliva and sebaceous glands. When licking their hair, cats smear this protein all over the body, which is spread into the air through hair and dander, and attaches to carpets, curtains, bed sheets, and clothes and people's hair. Fel d 1 is so sticky that it is difficult to eradicate even after a thorough cleanup. Finding an anti-allergic method targeting Fel d 1 can help most people.

Allergen-specific immunotherapy (AIT) is a tolerance–inducing treatment that changes the natural course of allergic diseases through immune regulation mechanisms.

Recently, researchers from the Luxembourg Institute of Health published an article titled "Comprehensive mapping of immune tolerance yields a regulatory TNF receptor 2 signature in a murine model of successful Fel d 1-specific immunotherapy using high-dose" in the journal Allergy, clarifying that high-dose specific adjuvant molecule CpG oligonucleotides can modulate the immune system's allergic response to the major cat allergen Fel d 1, thereby promoting human tolerance to cat allergic reactions.

In order to study the clinical effect of high-dose CpG adjuvant AIT, researchers first constructed a BALB/c OlaHsd mouse efficacy model allergic to Fel d 1, and then evaluated the efficacy of humans to withstand the maximum CpG dose under endotoxin-free conditions. By detecting the Fel d 1 specific antibodies in the serum of mice, it was found that the allergic mice treated with AIT showed lower IgE levels and higher IgA and IgG (anti-inflammatory effects) attributes, and the lung function and respiratory tract inflammation were obviously improved.

Subsequently, the researchers further studied the cytokines in mouse bronchoalveolar lavage fluid (BALF) and found that compared with untreated allergic mice, the levels of pro-allergic cytokines in mice treated with AIT reduced. This shows that in the preclinical model, AIT can reduce airway inflammation and reduce bronchial hyperresponsiveness.

In addition, the researchers noticed that there were a large number of immune cells involved in allergy regulation and tolerance in the tissues of mice treated with AIT, such as plasmacytoid dendritic cells (pDC), natural killer cells (NKs), and regulatory T cells (T-regs) and regulatory B cells (B-regs), which express high levels of tumor necrosis factor (TNF-α) and tumor necrosis factor receptor (TNFR-2) to inhibit specific immune responses and act as a "brake" on the immune system.

The researchers also found that AIT triggers a new and unique Treg, called biTreg, which can balance the response of effector cells to antigens. This further demonstrates the reversibility of allergic characteristics and the anti-allergic effect of AIT.

To apply these results to the clinic, researchers have developed a subcutaneous (sc) injection drug delivery system, which can reduce the number of airway eosinophils, more effective than traditional Intraperitoneal (IP) Injection, and can inhibit Th2 immune response.

Based on the maximum CpG dose tolerated by humans, the researchers optimized the ATI specific therapy for cat allergy, and developed a medically approved method of administration, laying the foundation for the development of new allergic immunotherapy.

In addition to AIT, scientists are still working on other methods.

1. Prevent cats from producing Fel d 1 by vaccinating them.

2. The antibodies that neutralize allergens are delivered directly into the cat's body through the cat food.