Cold virus linked to asthma and
"This suggests we might one day be able to reduce the incidence of allergy and asthma by vaccinating children against mild childhood diseases that traditionally haven't received much attention," says Farhad Imani, an instructor of medicine. Imani presented the findings in February at the annual meeting of the American Academy of Allergy, Asthma and Immunology.
Scientists have been aware of the link between viruses and allergies and asthma since the late 1970s, when studies showed that children exposed to viral infections were more predisposed to allergies and asthma, says Imani. But until now, no one had pinpointed the molecular steps leading from one event to the other.
That progression of steps, it turns out, is an unfortunate side effect of the cell's efforts to protect itself from viral infection.
When a virus infects immune system B cells, the cells do everything they can to survive, launching an anti-viral campaign, says Imani. They produce a special enzyme called anti-viral protein kinase to block viral replication. The anti-viral protein kinase also causes the cells to switch from producing antibodies called immunoglobulin types M and G to immunoglobulin type E, or IgE.
Each type of immunoglobulin plays a different role in helping cells fight intruders. IgE is thought to help fend off infectious parasites, says Imani. But IgE is also "a hallmark of allergies and asthma," says Imani. People who have B cells that produce IgE will be allergic "to whatever that group of B cells is sensitive to."
Imani and his colleagues exposed human B cells to vaccinia viruses and cold-causing rhino viruses. Some of the B cells started to produce IgE.
The researchers also found that weak viral strains were more likely to trigger production of IgE than were strong viral strains, or those that can cause grave illness. Though these results may seem surprising, says Imani, strong viruses apparently have found a way to circumvent the B cell's anti-viral system (which explains why they are more virulent), and thus they do not switch to IgE production.
A viral infection is not the only thing needed to cause allergies or asthma, notes Imani. "You also need a genetic background for susceptibility and exposure to an allergen." Nor do the scientists know whether a viral infection triggers every case of allergy or asthma. "At this point, we don't know whether a virus is required in 100 percent, 80 percent, or 50 percent of cases," says Imani.
"We're going to check every virus we can get our hands on," says Imani, "to see if our theory holds." --MH
Just check out the latest venture between the Hopkins Medical
Institutions and a company called InteliHealth. Located on the
World Wide Web at
http://www.InteliHealth.com, the newly launched site provides
a bonanza of consumer health information provided by Hopkins
medical experts and other authoritative sources, such as the
National Institutes of Health.
The site features health information in a variety of user-friendly formats. You can take a quiz on hypertension, retrieve a heart healthy recipe for banana-nut bread, and learn the day's pollen and pollution counts for your region.
The Health Encyclopedia offers information on illnesses from A (abscessed tooth) to Y (yersiniosis). In "Ask the Doc," Hopkins health professionals answer health questions submitted by the site's users. The site also contains the U.S. Pharmacopeia for the latest reports on new drugs; and several years of the Medline database, the most comprehensive collection of abstracts from medical journals. Finally, it provides telephone numbers for making patient appointments at Hopkins.
The new site is not, however, a substitute for those intimate chats between doctors and patients, says Ron Sauder, director of the Johns Hopkins Office of Consumer Health Information. "We're not making diagnoses," he says. "We're not prescribing drugs or treatments. We are providing information rather than advice. I don't think it is different from the Q & A columns written by physicians in many newspapers." And just as a reminder, the new Web site begins with a detailed disclaimer.
InteliHealth was formed last year to produce and distribute consumer health information. Aetna U.S. Healthcare provided a $25 million line of credit, in exchange for becoming the company's majority stockholder. The InteliHealth Web site is just the latest product of the joint venture. InteliHealth also recently began providing the content for the health channel on the PointCast Network, the online news service that continuously feeds news and advertisements to computers via screen savers. PointCast has 1.7 million subscribers.
InteliHealth has also signed a licensing agreement with CompuServe, which is expected to begin featuring a forum using Johns Hopkins sources by the end of the month, according to Sauder. CompuServe is the second largest online commercial service, with approximately 5 million subscribers worldwide.
The aim of the InteliHealth project is to inform consumers about health, to publicize the Hopkins name, and to generate revenue for Hopkins, says Sauder. InteliHealth makes money by selling advertising on its Web site and on the PointCast health channel. It also charges a fee for providing content to clients such as CompuServe. Hopkins, in turn, receives royalties on revenue generated by InteliHealth, and has equity in the company.
Among the products in InteliHealth's "future vision," says Sauder, is a service that will custom-design health information. For example, a subscriber might ask to receive regular reports on the latest research on type II diabetes. --MH
Managed care for AIDS
The program, Moore Options, was set to take effect in March, and is part of an upcoming statewide effort to capitate the costs of AIDS patients covered by Medicaid.
The Medical Institutions will receive a monthly reimbursement from the state for each patient in the program, expected to total about 500. That fee--$2,160 a month--will cover all medical services, with Hopkins assuming expenses above and beyond the capitation. "We feel comfortable that we can provide the care needed by that population at that rate," says Patricia Engblom, AIDS capitation program administrator. To ensure equal treatment, physicians won't know whether or not a patient is enrolled in the program.
John G. Bartlett, director of the medical school's Division of Infectious Diseases, says the arrangement was inevitable given the economics of chronic care. "We've always been convinced that this was a smarter way to deal with patients with a chronic disease," Bartlett says. "We have data to show that it's economically feasible. [We've] looked at our numbers and our organization and feel that we're a good risk, because of relatively low costs and a fairly tightly controlled network of services."
The Hopkins AIDS service offers an extremely broad range of care, from mental health to inpatient treatment. The only components Hopkins will contract out will be pharmacy and transportation services, he says.
The hospital will not have to absorb the costs of protease inhibitors, a new class of medicines taken as a so-called "cocktail" that can clear the bloodstream of HIV, at least temporarily. Many AIDS patients have benefited dramatically from the drugs. But the pills, which can exceed $15,000 a year, and must be taken indefinitely, also pose a significant financial burden for insurers. "The bill for protease inhibitors will be sent directly to Medicaid," Bartlett says.
As one of the first plans of its kind in the nation, Moore Options will bear the close scrutiny of officials from other academic medical centers and from health care organizations, Bartlett says. They will be watching to see how well the program balances cost control with quality of care. --AM
Four injections of the new cat allergy vaccine over two weeks reduce the watery eyes, itching, runny nose, and other feline-triggered symptoms familiar to allergy sufferers, researchers reported in February at the annual meetings of the American Academy of Allergy, Asthma and Immunology. In contrast, conventional allergy shots generally require 25 or more injections over three months. Conventional shots also run a greater (though small) risk of causing serious allergic reactions, including a potentially fatal response called anaphylaxis.
At the same meeting, a Hopkins team also reported that a new ragweed allergy vaccine requires only eight injections over the course of two and a half weeks. Conventional allergy therapy requires about two shots per week for 10 to 12 weeks, followed by two shots per month for several years.
An allergy attack is a type of immune reaction. In cat allergy, for example, immune cells called T cells recognize key regions on proteins--antigens--in cat dander. These key regions are called epitopes. The T cells then rally other members of the immune system, leading to a series of reactions that result in allergy symptoms.
The new cat allergy vaccine, which was designed by ImmuLogic
Pharmaceutical Corporation, is based on a twist to the immune
response. The vaccine contains two pure epitopes of the cat
dander antigen. When T cells encounter these epitopes that are
separated from the rest of the cat dander protein, they do not
respond and, in fact, even learn to tolerate the whole antigen.
Conventional allergy shots, which are extracts of cat dander, contain these epitopes, but in far more dilute and cruder form.
In their study, the researchers injected various doses of the new cat allergy vaccine or placebo into 271 cat-allergic volunteers. Six weeks after the treatment, each volunteer was then asked to spend an hour in a room inhabited by cats. The volunteers who had received the new vaccine reported significantly fewer allergic symptoms following the exposure.
The new ragweed allergy vaccine, which was also designed by ImmuLogic, uses a similar strategy. It contains only selective sections of the allergens responsible for ragweed allergy. -- MH
Written by Melissa Hendricks and Adam Marcus (MA'96)
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