Characterization of F21.A, a monoclonal antibody that recognize a leucocyte surface antigen for killer whale homologue to beta-2 integrin.

The specificity of F21.A, a monoclonal antibody raised against bottlenose dolphin leucocytes, was characterized in killer whale on the basis of immunoprecipitation of a protein of 94 kDa, as well as flow cytometric analysis. While minimally expressed on resting cells, F21.A labeled a homologue to beta-2 integrin in 89-97% of PMA-activated neutrophils, 53-66% of activated monocytes, and activated B cells but not T cells. Activation of neutrophils reached its maximum 10 min after PMA stimulation. F21.A did not label intracellular stores as did both cross-reacting anti-canine CD11b and CD18, suggesting that an activation-induced conformational change would expose a neoepitope recognized by F21.A. F21.A labeling was largely inhibited by pre-incubation with plasma, suggesting a binding site closely related to that for fibrinogen. In vitro phagocytosis and respiratory burst were almost fully inhibited upon pre-incubation with F21.A, demonstrating its functional importance. This antibody is foreseen as a possible valuable diagnostic and research tool in cetacean immunology.

In vivo cytokine production in murine listeriosis. Evidence for immunoregulation by gamma delta+ T cells.

Differential cytokine production by gamma delta+ T cells influences Th1 and Th2 responses. Here, we describe the in vivo kinetics of peritoneal and splenic gamma delta+, CD4+, and CD8+ T cell cytokine responses during primary and secondary Listeria infections. The data show differences in the kinetics of IFN-gamma-producing alpha beta+ splenocytes consistent with immunologic memory. Most noteworthy, however, was the elevated production of IL-10 by splenic gamma delta+ T cells in the red pulp and marginal zones that coincided with maximal IFN-gamma production and with a decrease in inflammation and tissue damage. This result implies a role for gamma delta+ T cells in the control of Th1 responses.