Immune response--on steroids

For all I’ve been through with melanoma, it’s ironic that that my immune system should be triggered so spectacularly by minor exposure to poison oak. I apparently got into some while weeding bushels of dead forget-me-nots from under my roses on Thursday, and by this morning my left eye was swollen shut and my face and neck on fire. The prednisone I’ve been prescribed is all that stands between my daily routine and insanity-inducing itchiness.

Allergies of any kind are merely an overreaction of the immune system. Specialized white blood cells are designed to attack things that are genuinely foreign, including some substances that would be harmless if not for the immune attack. While these cells have evolved to neutralize and eliminate foreign substances from our bodies, they can’t tell whether or not an invader is dangerous or not, so they sometimes vigorously attack harmless things—like the oil from poison oak that penetrates our skin. This process causes an inflammation that can be far more harmful than the foreign substance itself.

I’m no immunologist, but I know from my experience with interferon therapy that these white blood cells (lymphocytes) are pretty good at recognizing foreign substances, usually after they have been attacked by other specialized cells (macrophages). Lymphocytes pour out inflammation-causing proteins called cytokines. The macrophages become activated by the cytokines and attack everything in the vicinity, which can cause severe tissue damage. This process explains those nasty pustules that are beginning to display themselves so gloriously across my face.

A somewhat similar cellular drama plays out in people who have been prescribed interferon, as I was two years ago. When injected at high volume, this class of cytokine is meant to stimulate the activity of natural killer T cells—the shock troops in the lymphocytic army. Without this kind of help, the body will sometimes give cancer cells a free pass, not recognizing them as the nasty little bastards that they are. As cancer cells are essentially “self,” and not a foreign invader, the immune system needs help to neutralize them.

This free association between poison oak and cancer came to me last night as I was lying in a recliner with an ice pack draped across my throbbing face. I have a miraculous immune system to thank for keeping me alive, but it’s hard to feel too great about it at the moment. I hope the T cells that are assigned to chase down the melanoma lurking in my body are as successful as they have been during this intense encounter with poison oak.