This Article Full Text Full Text (PDF) All Versions of this Article: 2006-0195OCv1 36/1/94    most recent Alert me when this article is cited Alert me if a correction is posted Services 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 HighWire Citing Articles via Google Scholar Google Scholar Articles by Hansen, S. Articles by Wright, J. R. Search for Related Content PubMed PubMed Citation Articles by Hansen, S. Articles by Wright, J. R.

Surfactant Protein D Augments Bacterial Association but Attenuates Major Histocompatibility Complex Class II Presentation of Bacterial Antigens

Department of Cell Biology, Duke University and Medical Center, Durham, North Carolina; Medical Biotechnology Center, University of Southern Denmark, Odense, Denmark; and Mendel Center for Biomedical Sciences, Nicosia, Cyprus

Correspondence and requests for reprints should be addressed to Jo Rae Wright, Ph.D., Department of Cell Biology, Box 3709, Duke University Medical Center, Durham, NC 27710. E-mail: j.wright{at}cellbio.duke.edu

Surfactant protein D (SP-D) is a secreted pattern recognition molecule associated with lung surfactant and mediates the clearance of pathogens in multiple ways. SP-D is an established part of the innate immune system, but it also modulates the adaptive immune response by interacting with both antigen-presenting cells and T cells. In a previous study, antigen presentation by bone marrow–derived dendritic cells was enhanced by SP-D. As dendritic cell function varies depending on the tissue of origin, we extended these studies to antigen-presenting cells isolated from mouse lung. Flow cytometric studies showed that SP-D binds calcium dependently and specifically to lung CD11c-positive cells. Opsonization of fluorescently labeled Escherichia coli by SP-D enhanced uptake by lung dendritic cells. SP-D facilitated the association of E. coli and antigen-presenting cells by increasing the frequency of CD11+ cells associated with E. coli by up to 10-fold. In contrast to the effect on bone marrow–derived dendritic cells, SP-D decreased the antigen presentation of ovalbumin, expressed in E. coli, to ovalbumin-specific major histocompatibility complex class II–specific T-cell hybridomas by 30–50%. The reduction of antigen presentation did not depend on whether the dendritic cells were isolated from the lungs of nonstimulated mice or mice that had been exposed to LPS aerosols. Our results show that SP-D increases the opsonization of pathogens, but decreases the antigen presentation by lung dendritic cells, and thereby, potentially dampens the activation of T cells and an adaptive immune response against bacterial antigens—during both steady-state conditions and inflammation.

Key Words: lung • collectins • SP-D • opsonization • antigen presentation

CLINICAL RELEVANCE This work concerns SP-D's immunoregulatory role, and is important for understanding the disease mechanisms of many inflammatory disorders (e.g., asthma, pneumonia). It contradicts previous findings using in vitro-derived antigen-presenting cells.

 

This article has been cited by other articles:

				A. Baldan, A. V. Gomes, P. Ping, and P. A. Edwards Loss of ABCG1 Results in Chronic Pulmonary Inflammation J. Immunol., March 1, 2008; 180(5): 3560 - 3568. [Abstract] [Full Text] [PDF]

				A. M. Pastva, J. R. Wright, and K. L. Williams Immunomodulatory Roles of Surfactant Proteins A and D: Implications in Lung Disease Proceedings of the ATS, July 1, 2007; 4(3): 252 - 257. [Abstract] [Full Text] [PDF]