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This Article Full Text (Papers in Press[PDF]) All Versions of this Article: jmm.0.007385-0v1 58/7/951    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Trigo, G. Articles by Tavares, D. PubMed PubMed Citation Articles by Trigo, G. Articles by Tavares, D. Agricola Articles by Trigo, G. Articles by Tavares, D.

Leukocyte populations and cytokine expression in the mammary gland in a mouse model of Streptococcus agalactiae mastitis

ICBAS

¹ E-mail: dtavares{at}icbas.up.pt

Received October 22, 2008
Accepted March 6, 2009

Streptococcus agalactiae is a contagious mastitis-causing pathogen highly adapted to survive in the bovine mammary gland. This study used the BALB/c mouse model of S. agalactiae-mastitis to evaluate leukocyte populations in regional lymph nodes and cytokine expression in the mammary gland involved in the immune response against S. agalactiae. We found that the bacteria replicated efficiently in the mammary gland, peaking after 24 h and increasing by one hundred fold. Dissemination of bacteria to systemic organs was observed 6 h after infection. At the same time, a massive infiltration of polymorphonuclear cells and an increase in inflammatory IL-1β, IL-6, and TNF- were detected in mammary glands, indicating an early inflammatory response. A decrease in the levels of inflammatory cytokines in mammary glands was observed 72 h after infection accompanied by an increase in the levels of IL-12 and IL-10, which were related to a gradual decrease in bacterial load. An increase in the number of macrophages and B220+ lymphocytes and similar increases in both CD4+ and CD8+ T-cells in regional lymph nodes was observed, being most pronounced 5 days post infection. Moreover, increased levels of anti-S. agalactiae antibodies in the mammary gland were observed 10 days after infection. Overall, these data suggest that the host exhibits both innate and acquired immune responses in response to S. agalactiae mastitis.