IgA in the horse: cloning of equine polymeric Ig receptor and J chain and characterization of recombinant forms of equine IgA

As in other mammals, immunoglobulin A (IgA) in the horse has a key role in immune defense. To better dissect equine IgA function, we isolated complementary DNA (cDNA) clones for equine J chain and polymeric Ig receptor (pIgR). When coexpressed with equine IgA, equine J chain promoted efficient IgA polymerization. A truncated version of equine pIgR, equivalent to secretory component, bound with nanomolar affinity to recombinant equine and human dimeric IgA but not with monomeric IgA from either species. Searches of the equine genome localized equine J chain and pIgR to chromosomes 3 and 5, respectively, with J chain and pIgR coding sequence distributed across 4 and 11 exons, respectively. Comparisons of transcriptional regulatory sequences suggest that horse and human pIgR expression is controlled through common regulatory mechanisms that are less conserved in rodents. These studies pave the way for full dissection of equine IgA function and open up possibilities for immune-based treatment of equine diseases

Binding and Internalization of Herpes Simplex Virus-Antibody Complexes by Polymorphonuclear Leukocytes

We studied the interactions between rabbit polymorphonuclear leukocytes (PMN) and the RE strain of herpes simplex virus type 1 (HSV-1) to determine better the role of inflammatory cells in herpetic stromal keratitis. PMN were found to be nonpermissive for HSV replication and were unable to bind virus in the absence of antibody. However, PMN did bind and internalize HSV-antibody complexes in vitro as was demonstrated visually by electron microscopic studies and quantitatively by measurement of activity associated with radiolabeled HSV-antibody complexes. Virus used for immune complex formation was labeled with either 125 Iodine or 35 S-methionine. In some experiments, anti-HSV IgG used for immune complex formation was labeled with 125 Iodine before incubation with virus. Use of all three radiolabeling approaches resulted in the same general pattern of binding, indicating a requirement for both antibody and virus for interaction with PMN. The activity associated with PMN was increased by preincubation with complement. The results suggest an active role for PMN in controlling HSV infection through their ability to bind and ingest virus-antibody complexes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38230/1/1890200207_ftp.pd