Could Long-term Exposure To Allergen Cause Issues If HLA-B27 Is Positive?

Posted on Tue, 25 Feb 2014

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Tue, 25 Feb 2014 Answered on

Fri, 14 Mar 2014 Last reviewed on

Question : Could long-term exposure to allergen (cat) cause issues if you are HLA-B27 positive? Allergy to cats is mild and doesn't require medication, but becomes more accute for a day after a week without a cat.

Answered by Dr. Prahlad Duggal (4 hours later)

Brief Answer: Avoid exposure to an allergen as much as possible Detailed Answer: Hi, Thanks for the query. HLA-B27 positivity is usually related to various diseases, ankylosing spondylitis or IBD or some other diseases. The reason for the development of various diseases in association with HLA-B27 positivity is the likely cross reaction of body antibodies to various allergens with body's own molecules. But as such persons who are allergic to various allergens do not necessarily become more allergic or suffer from some other allergen also if they are HLA-B27 positive. Long term exposure to an allergen like cat may or may not lead to any symptoms independent of the HLA-B27 status. It is usually not advisable to keep on having exposure to a known allergen even if it is mild allergy. Exposure to an allergen leads to the development of antibodies against that allergen and those antibodies are body's reaction to fight that allergen. So, the increase in intensity of symptoms after a week without a cat but the reason may or may not be explainable as a linear relation is usually not there in such cases. Best strategy is to avoid exposure to an allergen altogether if possible or as much avoidance should be maintained as possible. feel free to ask another query. Regards

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Prahlad Duggal (55 minutes later)

Thank you. My main idea was to understand whether I am more susceptible to consequences of being exposed to an allergen just because I am HLA-B27 positive (since it appears SPA or SA symptoms have appeared, I wondered whether it can be related to the fact that I live with the cat for more than 5 years). If it shouldn't be related in any way (i.e. trigger the immune response to other, even not related, antigens), I am very glad. Regarding increased intensity of symptoms (occasional sneezing) - it appears that if I travel away from home (so get rid of allergen) for a week and then come back (allergen is back), symptoms reappear for a day or two and then subside again, so I am able to live normal life without any antihistamines or similar. Thanks for clarification. I will close the discussion.

Answered by Dr. Prahlad Duggal (1 hour later)

Brief Answer: Descriptive Detailed Answer: Thanks for the clarification. There is usually no relation of one's symptoms of allergic rhinitis with HLA status and your apprehension of you being more susceptible to allergens because of you HLA positive status is an unlikely scenario. So you should relax on that aspect. Your other description of appearance of symptoms on coming back home after a break of few days is self explanatory as a sustained exposure helps body in controlling the things. It is nice that you need not have any medicine for the symptoms. Regards

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar