AJP - Lung Cellular and Molecular Physiology, Vol 267, Issue 6 712-L719, Copyright © 1994 by American Physiological Society
Surfactant protein A stimulation of inflammatory cytokine and immunoglobulin production
S. G. Kremlev and D. S. Phelps
Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey 17033.
Pulmonary surfactant plays a variety of roles related to the regulation of
immune function in the lung. Of particular interest in this regard is
surfactant protein A (SP-A), a calcium-dependent lectin. We have reported
previously that SP-A enhances concanavalin A-induced proliferation, and in
this study we examined the secretion of tumor necrosis factor-alpha
(TNF-alpha), interleukins 1 alpha, 1 beta, and 6, and interferon-gamma by
human peripheral blood mononuclear cells. Levels of all of the cytokines
except interferon-gamma were increased by SP-A. In rat peripheral blood
cells, splenocytes, and alveolar macrophages we found a similar enhancement
of TNF-alpha release by SP-A. In combinations of SP-A and surfactant
lipids, the increased levels of TNF-alpha resulting from SP-A treatment
decreased as the lipids increased. At higher relative concentrations of
SP-A, the lipids had little or no effect. SP-A also enhanced the production
of immunoglobulins A, G, and M by rat splenocytes. Levels of each isotype
were increased severalfold over control levels. These data demonstrate that
SP-A is capable of modulating immune cell function in the lung by
regulating cytokine production and immunoglobulin secretion.
