Cold urticaria is the occurrence of hives precipitated by exposure to cold; often this condition is associated with an under­lying disease.

The following may be used to relieve the pain of sinusitis or middle-ear allergy: 1. Nasal decongestants, whether used locally or orally, help open clogged tubes to the sinus cavities and the middle-ear chambers. 2. Heat applied to the local sinus area and the ears—in the form of a heating pad, hot cloths, or warm mineral oil solution in the ears—provides some relief. 3. Medications for pain—such as aspirin and acetaminophen (Tylenol and Valadol)—may be taken until medical attention can be obtained. 4. Antihistamines can be used to treat the underlying allergic rhinitis. 5. Avoid swimming, diving, and trips to high elevations until the condition improves. Summary Allergy emergencies are not common, and they are rarely fatal. Those that do require immediate attention are anaphylaxis, a general­ized, allergic shocklike reaction; laryngeal, or tracheal, edema (swell­ing of the windpipe); and severe asthma, or bronchospasm. Epinephrine by injection is the drug of choice in all three emergencies. Although allergy emergencies have numerous causes, a general knowledge of them can enable the allergy sufferer to prevent recur­rences. Other related allergic illnesses, while discomforting and sometimes alarming, are not life-threatening. Self-treatment measures are available to provide relief until more extensive medical attention can be obtained. Allergy emergencies can be treated successfully, and some can often be prevented. Unlike some injuries and certain illnesses, the outlook for complete recovery is good.

An anaphylactic reaction is a state of shock caused by a severe allergic reaction, which results in sudden collapse and, occasionally, in death.

A basophil is a type of white cell that circulates in the blood. Cells of this type have surface receptors for the allergic (IgE) antibodies and participate actively in an allergic reaction. Upon ex­posure to an allergen, the reaction between the allergen and the anti­bodies on the surface of the cell initiates a series of intracellular events that culminate in the release of histamine and other chemicals responsible for allergic symptoms.

A psychogenic disorder is one originating in the mind or in mental conflict.

See Scratch Test.

Antigens are substances that induce a specific immune response. The clearest" response is the appearance of antibodies in blood serum and other body fluids. The antibodies produced in this response rec­ognize the antigen that stimulated their production; thus they can neutralize the antigen’s harmful effects, if any, hastening elimination of the antigen from the body. How is this complex sequence of events set in motion? When an antigen enters an animal, some of it is absorbed by the ever-present mac rophages. The macrophages "process" the antigen, presumably enhancing the ability of some of the antigen to interact with lympho­cytes. The macrophages then present the antigen to T and В cells; В cells bear a surface receptor that recognizes a specific region of the antigen, called the determinant. The В cells react with the antigen, thereby initiating an immune response. The B-cell receptor is, in fact, an antibody, the same one the В cell will eventually manufacture. Each В cell has only one type of antibody on its surface; each В cell (and its progeny, or "daughter," cells) can produce only that anti­body molecule. Protein antigens may have several different deter­minants; this enables them to stimulate many different В cells to di­vide, to differentiate, and to generate clones (identical daughter cells) of antibody-secreting plasma cells. Again, each cell secretes an antibody identical to the receptor on the В cell from which it was derived. Moreover, each unique antigenic determinant on an antigen can elicit antibodies that vary in their affinity (or ability to bind) and specificity (ability to recognize a particular antigen and distinguish it from the others). The quantity and quality of antibody produced in response to a given antigen depend largely on the nature and amount of the antigen, the route it takes in the body, and the form in which it appears. In the case of pollen allergy, for example, natural exposure to the minute amounts of antigen present in inhaled pollen grains causes a signifi­cant, though still minute, amount of an antibody to be produced. This antibody is called reaginic, or IgE, antibody. In contrast, when an extract of pollen containing relatively large amounts of the same antigen is injected for treatment, relatively large amounts of an anti­body that blocks the allergic reaction will be produced. We are just beginning to understand the difference between regulation of the В cells that make the reaginic antibody and regulation of the В cells that make the blocking, or IgG, antibody. For one thing, helper T cells and suppressor T cells act differently on the two groups of В cells. It is well known that genetic factors influence immune responses; for example, allergies occur more often in some families than in others. Moreover, some genes—called immune response genes—are dedicated to controlling the response to particular antigens, whereas some control the type and amount of an antibody that can be made, some the number and distribution of lymphocytes, and some the cell-surface molecules (such as transplantation antigens) involved in the recognition of antigens. In an animal that has never encountered a particular antigen, there resides a small population of В cells committed to respond to that antigen by virtue of its specific surface receptor. When the antigen enters the body and encounters the appropriate cells, it causes these cells to divide. Some differentiate and become antibody-secreting plasma cells. The concentration of antibody in the serum rises abruptly, and the presence of this antibody increases the rate of anti­gen elimination. But plasma cells survive only a few weeks. As they die, the serum antibody level subsides, ending this primary immune response. Some В cells, however, survive as an expanded set of specifically committed, long-lived, "memory" В cells. The animal mentioned at the beginning of this paragraph is now primed for a heightened, more rapid, secondary response to the same antigen. Here we come to the explanation for the two principal characteristics of the immune response—memory and specificity. The initial encounter with an antigen leaves the animal (or human) with a greatly ex- panded population of lymphocytes (both T cells and В cells) that can respond when that antigen is encountered again.

cook bacon slowly. Add onion, and cook until clear. Add tomatoes, water,and seasonings. Bring to a boil. Add rice and boiling liquid, gently stirring with fork until the mixture comes to a boil. Cover tightly, reduce and let simmer for 20 minutes. Fold in the diced meat when rice is tender and dry. Heat to serving temperature and add cheese if allowed. Serves 4.

Wool fibers can irritate the skin or cause allergy by inhalation or contact. Such fibers are more common in atopic dermatitis than in rhinitis or asthma.

Trees, important in respiratory allergy, are divided into the following families: conifers (Pinaceae); maple (Aceraceae); birch (Betulaseae); elm (Ulmaceae); willow and poplar (Salicaceae); wal­nut and hickory (Juglandaceae); and oak (Fagaceae). Tree pollen is an important cause of spring hay fever symptoms. The conifer family includes pine, cedar, juniper, and black hem­lock, among others. Conifers are the most common trees in Canadian forests, in the pinelands of the American Southeast and at lower elevations of the Rocky Mountains. Pollen production is substantial. Despite the widespread belief that pine pollen has strong allergenic qualities, the pollen is of little importance in respiratory allergy. The maple family is widely distributed throughout the United States. Most maples are better suited for insect pollination, but they also depend partly on the wind. Pollination occurs in March and April and may produce symptoms common to early spring. Birch, ironwood, alder, and hazelnut are members of the birch family. Abundant throughout the American Northeast, they produce significant amounts of pollen and are a major cause of hay fever in the early spring. Distributed virtually throughout the United States, elms are among the earliest flowering trees in the spring. The elm produces large amounts of pollen, which is a cause of hay fever. In recent years the number of elms has decreased sharply because of a widespread fungus infection. Willows are partially adapted to insect pollination, which occurs during March, April, and May. Poplars shed large amounts of pollen, are wind-pollinated, and cause hay fever in the early spring.
The walnut-hickory family includes walnut, hickory, and pecan trees. These species are common in the eastern, southern, and central states of the United States. The trees pollinate during the late spring and are a major cause of hay fever. The oak family is made up primarily of oaks and beeches. These trees are widely distributed over the United States and produce an abundant amount of pollen, which is a major cause of hay fever during April and May.