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AUTOLOGOUS CONDITIONED SERUM (ACS)

Autologous conditioned serum (ACS), also known as IRAP (IL-Ra or interleukin-1 receptor antagonist protein), is a popular treatment strategy for horses, especially those that are refractory to corticosteroid injection.

The exploration of IRAP as a treatment for synovitis, osteoarthritis and rheumatoid arthritis began shortly after its first published characterization in 1984. The ability of this molecule to act as both a symptom- and disease-modifying agent in various species (including horses and humans) has prompted its clinical application as a treatment for joint disease.

IRAP

IRAP works by blocking the destructive effects of interleukin-1, which is a major mediator of joint inflammation and disease.

The goal behind IRAP treatment is to use the body's own inflammation-fighting cells to reduce arthritis rather than the synthetically-produced antiinflammatory medications that we buy in a bottle. Because antiinflammatory cells are produced by the host body itself, we can often expect an improved degree of response as well as a longer duration of response.

Autologous versus Allogeneic

The primary difference between allogeneic and autologous cells lies in their source. Allogeneic therapies are manufactured in large batches from unrelated donor tissues (such as bone marrow) whereas autologous therapies are manufactured as a single lot from the patient being treated.

The first scientific publication highlighting the benefits of IRAP appeared in 2003. A newer version (cleverly named IRAP II) is most commonly employed at present. Both IRAP products are prepared from the horse's blood, which is incubated for a period of 24 hours in the presence of glass beads that stimulate production of IL-1Ra. Conditioned serum is subsequently recovered and injected back into the arthritic joint(s) to reduce inflammation and improve comfort.

Click HERE to review common joint therapies in the horse.

Click HERE to review the basics of degenerative joint disease (DJD) in the horse.