Bobbie Boyd

Bovine dendritic cells generated from monocytes and bone marrow progenitors regulate immunoglobulin production in peripheral blood B cells.

We examined whether bovine monocyte-derived and bone marrow (BM) dendritic cells (DCs) regulate antibody production in activated peripheral blood B cells. DCs were generated from monocytes and BM progenitors in the presence of bovine recombinant granulocyte/macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4). Monocyte-derived DCs promoted B cells activated by the anti-CD3 triggered CD4(+) T cells or through immunoglobulin M (IgM) receptor to increase the level of IgG secretion. Furthermore, the addition of DCs triggered B cells activated through IgM receptors to produce IgG2 and IgA, thus inducing an isotype switch. BM-derived DCs increased the production of IgG in B cells activated by the anti-CD3 triggered CD4(+) T cells, but unlike monocyte-derived DCs did not have any effect on B cells activated through surface IgM. These data suggest that the regulation of humoral immune responses in cattle depends on the origin of DCs and the mode of B cell activation.

Histological enzyme and flow cytometric analysis of channel catfish intestinal tract immune cells.

Channel catfish, Ictalurus punctatus, gastrointestinal tract leukocytes were characterized using flow cytometry, histochemistry, and enzyme staining techniques. Cells obtained from the lamina propria by collagenase digestion were found to be primarily neutrophils, with fewer than 6% B lymphocytes as determined by flow cytometry. Histochemical and enzyme stains were used to determine leukocyte distribution in gastrointestinal tract tissue. Macrophages and T lymphocytes were observed throughout the gastrointestinal tract. As in flow cytometry studies, few B lymphocytes and many neutrophils were observed in the channel catfish gastrointestinal tract. Since cells involved in specific immunity appear to be limited in gastrointestinal tract tissue of channel catfish, we speculate that catfish may rely more heavily on a highly developed innate response for intestinal mucosal immunity than other teleost species studied.

Bovine monocytes induce immunoglobulin production in peripheral blood B lymphocytes

Although a role for monocytes and monocyte-derived dendritic cells (DC) in the activation of T cells is well established, it is less clear to what extent DC and their precursors, monocytes, regulate B cell immune responses. Here we show that regulatory mechanisms similar to those in humans are in place in the bovine immune system. In vitro culture of bovine monocytes with bovine B cells activated by the anti-CD3 triggered CD4+ T cells or through immunoglobulin (Ig) receptor crosslinking induces B cell Ig secretion. Unlike bovine monocyte-derived DC, monocytes do not promote Ig class switching to IgG and IgA in activated peripheral blood B cells. These results suggest that bovine monocytes are capable of directly inducing Ig secretion in activated bovine peripheral blood B cells, but do not provide the signals for B cell Ig class switching.

A cytochemical, light and electron microscopic study of the peripheral blood leucocytes of hybrid surubim catfish (Pseudoplatystoma corruscans x Pseudoplatystoma fasciatum)

This paper describes the results of our initial studies with hybrid surubim catfish leucocytes and suggests that the techniques used may have further application. According to size, shape, staining patterns and ultrastructure, five blood leucocyte types were identified in the peripheral blood of surubim: lymphocytes, thrombocytes, monocytes, neutrophils and eosinophils. A tentative plasma cell was also observed by electron microscopy. Haematocrit and leucocrit were also analysed and reference values for these parameters are proposed. The results obtained in the present study should be useful to support further evaluations, and to develop or refine methods to properly evaluate the health status of this fish.

Intracellular signaling events in superoxide generation and adhesion of channel catfish, Ictalurus punctatus rafinesque, neutrophils to the extracellular matrix protein fibrinogen

Activation of channel catfish neutrophils is essential if these cells are to participate in adhesion to extracellular matrix proteins or generate intracellular superoxide for killing of microbes. Various signaling pathways are required for these activities to occur. The objective of this study was to identify components of the signal transduction pathways in channel catfish neutrophils. A23187, bryostatin, and phorbol dibutyrate (PDBU) all induced catfish neutrophil adhesion to fibrinogen coated plates and the adhesion could be significantly reduced when neutrophils were pretreated with staurosporine (1 x 10(-7) M). Staurosporine was the only inhibitor used in the study that inhibited or reduced PDBU-induced adhesion of catfish neutrophils to fibrinogen. Phorbol dibutyrate at the concentrations used in the adhesion assay was the only stimulant that caused generation of intracellular superoxide and therefore was the only stimulant used in the remainder of the study. Aristolochic acid (1 x 10(-4) and 3 x 10(-5) M) + PDBU and staurosporine (1 x 10(-7) and 1 x 10(-8) M) + PDBU caused a significant decrease (p < or = 0.05) in PDBU-induced intracellular oxygen generation. The role of protein kinase C and phospholipases in channel catfish neutrophil adhesion and superoxide generation are discussed.

Generation, characterisation and applicability of a monoclonal antibody to hybrid surubim catfish Pseudoplatystoma corruscans (Agassiz) × Pseudoplatystoma fasciatum (Linnaeus) immunoglobulin

Monoclonal antibodies (mAb) against hybrid surubim immunoglobulin (IgM) were produced. Screening, with an indirect enzyme-linked immunosorbent assay (ELISA), revealed three probes: PSIg 10, PSIg 13 and PSIg 28 specifically reacting to surubim IgM. No species cross-reactivity was found. Isotyping revealed these probes as belonging to the IgG2b/κ subclass, and recognising, exclusively, the heavy chain of surubim IgM on immunoblotting. The most interesting mAb, PSIg 13, was employed to detect, for the first time, Ig-bearing cells of surubim in peripheral blood, spleen and head-kidney by FACS analysis and immunocytochemistry. The mAb raised here recognises the antigen in its native form, as denatured heavy-chain subunits and when expressed in living and fixed cells.