Allergic to Spunk

For about two years in high school, I would occasionally break out into pretty severe hives. I would first notice a mild itch on my wrists or ankles, and I would know that the hives were coming if I gently scratched my forearm and raised red streaks were left behind (I have a picture somewhere of a large inflamed smiley face I drew on my chest during one of these episodes). A dose or two fo Benedryl would completely knock the hives down, but left untreated, they would spread over my entire body. It was almost certainly an allergic reaction, but despite a battery of tests at an allergist's office, I never did learn what the offender was. These hives weren't pleasant, but in truth, I'm pretty fortunate when it comes to allergies. allergy (Source - sorry I resorted to the LOLcats, but as you'll see, most potential images for this story would be decidedly NSFW)

Fifty million other Americans aren't so lucky*. From relatively benign** seasonal allergies, to life threatening food allergies, humans can be allergic to just about any foreign molecule and allergies of all sorts are on the rise. On twitter the other day, Christie Wilcox mentioned that a friend that was curious about a rarely talked about, though surprisingly common allergy: Seminal Plasma Protein Allergy (SPPA). Also known as being allergic to sperm.

Actually, "sperm allergy" isn't quite right. Semen can be divided into two components: The sperm themselves are specialized cells that carry a half-compliment of genetica material, but they swim in seminal fluid (mostly secreted by the prostate gland), and it's proteins in this fluid that causes the allergy. The only recorded cases I could find were women, but this makes perfect sense. Allergies are directed at foreign substances, and seminal fluid is hardly foreign to us males.

Like most allergies, SPPA is thought to be caused by the production of specialized antibodies called IgE. Instead of floating around in the blood looking for a target, IgE gets picked up and held on the surface of mast cells. Mast cells are filled with nasty chemicals like histamines and inflammation-inducing cytokines, and are programed to spew out massive quantities when they see a foreign particle through their bound IgE. When directed against worms and other parasites, this is great, but when mast cells flip out over pollen or peanuts, misery ensues. The severity of documented semen allergy runs the gamut from mild itching and burning after sex to life-threatening systemic (whole-body) allergic reactions, including extreme fatigue, hives, shortness of breath and vomiting.

But it's hard to get good numbers on just how common this allergy is. This review from 2004 calls it a "rare phenomenon" in the title and only found 80 reported cases in the medical literature. However, a different review noted:

The incidence of human semen allergy is probably higher than reported because of lack of recognition in the medical community and underreporting by patients.

They mentioned a paper from 1997 with possibly the greatest author list ever (Bernstein, Sugumaran, Bernstein and Bernstein) managed to find 130 women with "probable" SPPA in a single study. The many Bernsteins gave questionnaires to about a thousand women with symptoms consistant with SPPA, and determined that about 25% had "possible" SPPA and 12% had "probable" SPPA - the criteria for the latter group was the ability to completely eliminate the symptoms by using a condom.

That's the good news for sufferers - the most effective treatment (condoms) is incredibly easy***. The bad news comes if a woman wants to get pregnant. Even if the symptoms aren't that severe, the resulting inflammation can make conception nearly impossible. There's been some success with desensitization - small injections of the offending substance in controlled environments can make the body figure out that the allergen isn't a threat - but this doesn't work in all cases. Thankfully, it seems that in vitro fertilization can be effective for couples that want to conceive, but this is just one more example where the over-exuberance of the immune system can make life miserable.

Later this week, I'll tell you about some truly bizarre case studies I ran across while researching this post - from a woman allergic to her husband's sweat to sexually-transmitted food allergies. Stay tuned!

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* Actually, I'd probably be lumped into that statistic too ** Seasonal allergies can also be debilitating for some, but for most people it's merely an irritation. *** Though I did find this case report of a woman with an allergy to semen AND latex. That's just excessive.

References: Bernstein JA, Sugumaran R, Bernstein DI, & Bernstein IL. (1997) Prevalence of human seminal plasma hypersensitivity among symptomatic women. Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology, 78(1), 54-8. PMID: 9012622

Ludman, B. (1999) Human Seminal Plasma Protein Allergy: A Diagnosis Rarely Considered. Journal of Obstetric, Gynecologic, Neonatal Nursing, 28(4), 359-363. DOI: 10.1111/j.1552-6909.1999.tb02003.x

Resnick DJ, Hatzis DC, Kanganis P, Liccardi FL, Lee-Wong M, & Bernstein JA. (2004) The approach to conception for women with seminal plasma protein hypersensitivity. American journal of reproductive immunology (New York, N.Y. : 1989), 52(1), 42-4. PMID: 15214941

Shah, A., & Panjabi, C. (2004) Human seminal plasma allergy: a review of a rare phenomenon. Clinical Experimental Allergy, 34(6), 827-838. DOI: 10.1111/j.1365-2222.2004.01962.x