Paris, France, Monday 31 October 2005 - Infection with a bacteria from the Chlamydia family may be linked to the development of a type of lymphoma which affects the tissues surrounding the eye, according to results released at the 13th European Cancer Conference (ECCO).
Several infectious agents have been pinpointed as potential risk factors for lymphoma development. Members of the Chlamydia genus of bacteria, in particular, may play a role in tumour development through their involvement in a wide spectrum of human diseases that cause persistent infections. A well documented relationship already exists between the Chlamydia strain, C. trachomatis, and the development of cervical cancer. Similarly, the respiratory infectious Chlamydia bacteria, C. pneumoniae, has a known association with lung cancer.
New data showcased at ECCO stem from a study which set out to confirm the suggested association between the Chlamydia strain, Chlamydia psittaci, and development of ocular adnexal lymphoma (OAL). C. psittaci is the etiological agent of psittocosis, a human lung infection caused by exposure to infected birds and potentially also deriving from household pets such as cats which are known carriers of the bacteria.
Between 2003 and 2004, DNA was extracted from the 33 OAL cases identified at the Asian Medical Center in Seoul, Korea. DNA extraction was also undertaken for a further 21 cases of a comparable, yet non-cancerous condition, non-neoplastic ocular adnexal disease (NNOAD). The extracted DNA was analysed using a touchdown enzyme time-released polymerase chain reaction technique to isolate the presence of the three Chlamydia strains – C. psittaci, C. trachomatis and C. pneumoniae.
The results show that C. psittaci infection is highly correlated with OAL. C. psittaci was found in 78% of all OAL cases, yet observed in only 23% of cases of the non-cancerous disease NNOAD. Infection with C. trachomatis or C. pneumoniae was either non-existent or present at a very low rate in both OAL and NNOAD. Of the C. psittaci infections analysed, a total of six distinct bacterial sequences were identified.
Study author, Dr Changhoon You from the Asian Medical Centre, Seoul commented, "Certain subtypes of low grade lymphoma are thought to be caused by some antigenic stimuli, for example, Helicobacter pylori (H. pylori) induced gastric low grade MALT lymphoma, Hepatitis C (HCV) related marginal zone B-cell lymphoma, and C. psittaci - induced ocular adnexal lymphoma. Other types of low grade lymphoma may be related with some antigenic stimuli that have not been identified so far. In the future, eradication of the antigenic stimuli could be a common treatment method of low grade lymphoma, replacing current cytotoxic chemotherapy or radiation."
OAL belongs to a group of lymphomas known as mucosa-associated lymphoid tissue (MALT) lymphomas. Cellular changes that lead to the development of these lymphomas result from aberrant immune responses. Infectious agents such as C. psittaci can hence function as contributory factors in MALT lymphoma pathogenesis.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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