Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/1998
Publication Date: N/A
Interpretive Summary: Immunoglobulins are major molecules that mediate immune responses. Their major role on white blood cells is to form bridges between bacteria and neutrophils, a form of a white blood cell that protects the body from bacterial infection. Once these bridges are formed, the bacteria is handcuffed to the neutrophil and is quickly eaten. Researchers in the Immunology and Disease Resistance Laboratory discovered that not only do certain immunoglobulins form bridges, but that they also act like switches. They cause the neutrophils intracellular machinery to turn on and begin to signal proteins in the cell to direct their attention of getting ready to do battle with the invaders. The neutrophil then transports these proteins to the surface where they become important docking stations for more immunoglobulins, allowing for the building of more bridges between bacteria and neutrophils. This discovery will allow researchers to devise strategies for increasing the types of immunoglobulins needed to form bridges between neutrophils and bacteria. Quick removal of bacteria by neutrophils will prevent bacteria from infecting dairy cows.
Technical Abstract: In this study, changes in intracellular free calcium concentrations and protein tyrosine phosphorylation (PTP) induced by immunoglobulin binding to bovine neutrophils (PMN) were investigated. Purified bovine IgG, IgG1, IgG2, IgM and heat aggregated IgG (aIgG) were used. IgG1 alone or crosslinked with a second antibody did not induce changes in calcium and PTP. IgG2 alone or crosslinked with a second antibody and aIgG induced a strong PTP response without changes in calcium. Crosslinking of IgG caused a rapid calcium increase of 91 nM without PTP response. IgM did not induce calcium influx or PTP responses. However, crosslinking IgM with anti-bovine IgM resulted in an increase of 115 nM in calcium and a strong PtP response on 45, 55, 100 and 115 kD proteins. Anti-bovine IgM antibody alone induced a similar calcium influx and PTP response, indicating a high occupancy of IgM on bovine PMN surfaces. These results are consistent with the major opsonization role of IgG2 and IgM in the bovine. Binding of these opsonic antibodies may trigger pathways for effective PMN phagocytosis.