Equine Secretory IgA and Secretory Component

Abstract

A complete secretory immunologic system has been identified in the equine species. It is characterised by the presence of a secretory component either bound to secretory IgA (SIgA) or remaining in the free form (FSC). The mean molecular weights of SIgA, serum IgA and FSC have been estimated. The homology of the equine and human IgA classes have been demonstrated by cross-reaction with anti-human IgA antisera. A quantitative study of equine immunoglobulins in various fluids have shown that SIgA is predominant in saliva, mature milk, nasal and lacrimal secretions, but not in colostrum. In vitro binding of human and bovine FSC is found to occur mostly with the polymeric form of equine serum IgA.

Immunoglobulin isotypes in sera and nasal mucosal secretions and their neonatal transfer and distribution in horses

“…35 Receptor-mediated uptake of immunoglobulin isotypes by mammary gland cells of swine has not been studied, but it has been shown that almost all colostral IgG and as much as 40% of colostral IgA in swine are of serum origin. [16][17][18] As expected, and in agreement with results of earlier studies, concentrations of all immunoglobulin isotypes (except IgGc) in equine colostrum were several times higher than serum concentrations. 36 We found that concentration of IgA increased and that of IgG decreased in mare' s milk during the first 28 days after parturition, suggesting that lacteal IgA is locally produced, and colostral IgG is derived from serum.…”

“…Moreover, the values may also be affected by the different assay methods used to determine isotype concentrations. 27 The combined serum IgGa, IgGb, and IgGc concentrations for horses (13 to 53 mg/ml) and ponies (18 to 35 mg/ml) in the present study were higher than total IgG concentrations reported earlier for Thoroughbreds and Quarter Horses (7 to 20 mg/ml), [13][14][15]28 whereas IgA concentrations (0.1 to 1.3 mg/ml) were lower than values reported by others (0.6 to 3.5 mg/ml, 14 1.5 to 4.8 mg/ml, 15 and 0.8 to 3 mg/ml 16 ). 14 Serum IgG(T) concentrations in horses in the present study (1.0 to 9.6 mg/ml) were higher than values in Thoroughbreds (0.7 to 4 mg/ml) reported by Rouse 28 but similar to values in Thoroughbreds reported by Kent and Blackmore 12 and in Quarter Horses reported by McGuire and Crawford.…”

“…36 Immunoglobulin A is found at higher concentrations than IgG in swine milk and is believed to be of local origin. [16][17][18] However, these results are in contrast to results of a previous study, 15 which indicated that concentrations of colostral IgGa, IgGb, IgGc, and IgG(T) in Quarter Horses on day 0 (immediately after parturition) are less than serum concentrations measured at the same time. This finding confirms results of previous studies that indicate IgA is the dominant immunoglobulin isotype in equine milk.…”

Immunoglobulin Transport and Immunoglobulin Receptors

“…Most prominent among these is the lactating mammary gland. SIgA is the major Ig of colostrum and milk from many mammalian species, where it contributes to passive immunity of the suckling young (Bienenstock and Strauss, 1970;Lamm and Greenberg, 1972;Pahud and Mach, 1972;Nagura et al, 1978;Hanson, 1982;Brandtzaeg, 1983b;Sheldrake et al, 1984;Hahn-Zoric et al, 1989;Cruz et al, 1991;Hayani et al, 1991;Goldblum and Goldman, 1994;Giugliano et al, 1995;Rosato et al, 1995;Demmer, 1999, 2000;Kumura et al, 2000;van der Feltz et al, 2001;Taylor et al, 2002;Rincheval-Arnold et al, 2002b). As described above (see previous section, Transport of Polymeric Ig by the Polymeric Ig Receptor), an early study of allotype markers in colostral IgA of rabbits provided direct evidence for local assembly of SIgA in the mammary gland (Lawton and Mage, 1969).…”

Homotypic and heterotypic serum and milk antibody to rotavirus in normal, infected and vaccinated horses

“…Absolute concentrations of the various immunoglobulin isotypes in mares' milk have been established (Rouse and Ingrain, 1970;Pahud and Mach, 1972;McGuire and Crawford, 1973 ) and IgA shown to be predominant. However, there is no information on the specific antibody titres to endemic enteric pathogens or other antigens, beyond the colostral period.…”