Coxiella Burnetii Infection Elevates B-Cell Non-Hodgkin Lymphoma Risk

Researchers suggest screening for lymphoma in patients with Q fever in light of the strong link between the two entities

medwireNews: Coxiella burnetii, the bacterium responsible for the zoonotic Q fever infection in humans, is associated with an increased risk of developing B-cell non-Hodgkin lymphoma, research suggests.

Researcher Didier Raoult, from Aix-Marseille Universite in France, and colleagues explain that previously lymphoma was considered a risk factor for persistent Q fever, but the incidence of follicular B-cell lymphoma in a successfully treated Q fever patient prompted the team to investigate the reverse relationship.

According to the French National Referral Center for Q fever database, 1468 patients were diagnosed with Q fever between 2004 and 2014. And analysis of stored specimens showed that B-cell lymphoma developed in seven (0.48%) patients, including the index case, the majority of whom were male (71%). Six patients had diffuse large B-cell lymphoma (DLBCL) and one had follicular lymphoma.

Using data on cancer incidence in the general population from the 2012 Francim national registry, the study authors found an excess risk of developing DLBCL and follicular lymphoma in patients with Q fever compared with the general population, with standardised incidence ratios of 25.4 and 6.7, respectively.

Moreover, multivariate analysis showed that the risk of developing lymphoma was a significant 9.35-fold higher in the 440 patients with persistent focalised infection than in those without.

C. burnetii was detected in all CD123+ plasmacytoid dendritic cells isolated from lymphoma patients whereas in patients with lymphadenitis, such cells were “rare and none of them were infected”, the team reports.

Serum levels of interleukin (IL)-10 were significantly elevated in samples from lymphoma patients (n=5) compared with lymphadenitis patients (n=48), those with acute Q fever without valvulopathy and progression to persistent focalised infection (n=26) and healthy controls (n=11), at a median of 25.3 pg/mL versus 15.5 pg/mL, 10.4 pg/mL and 6.1 pg/mL, respectively.

And among Q fever patients, serum IL-10 levels were significantly higher in those with than without lymphoma, at 25.3 pg/mL versus 12.7 pg/mL.

“The specific [plasmacytoid dendritic cell] infection and increased IL10 levels in patients with Q fever-associated lymphoma suggest an alteration of the immune signals within the lymphoma microenvironment”, write Didier Raoult in Blood.

Although they cannot conclude that Q fever directly causes lymphoma, nonetheless the researchers say that the “the link between Q fever and lymphoma that we evidence herein should not [be] neglected since early diagnosis of lymphoma would result in improved outcomes of Q fever patients.”

The team suggests that “[s]creening for early lymphoma diagnosis should be considered in the management of patients with Q fever, especially those with persistent focalized infections.”

Reference

Melenotte C, Million M, Audoly G, et al. B-cell non-Hodgkin lymphoma linked to Coxiella burnetii. Blood 2015; Advance online publication 13 October. doi:10.1182/blood-2015-04-639617

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