Page 711 - Veterinary Immunology, 10th Edition

VetBooks.ir Adaptive Protective Mechanisms

Both antibody- and cell-mediated immune processes protect body
surfaces. The antibodies produced on mucosal surfaces include IgA,

IgM, IgE, and IgG. Some of these, most notably IgA and possibly
IgM, act by immune exclusion (see Fig. 22.4). The others, especially
IgE and IgG, destroy antigen within the surface tissues by immune
elimination.

Immune Exclusion

Immunoglobulin A

IgA predominates in surface secretions. At least 80% of all plasma
cells are found in the lamina propria, and together they produce
more immunoglobulin A than all other immunoglobulin isotypes

combined. IgA is found in enormous amounts in saliva, intestinal
fluid, nasal and tracheal secretions, tears, milk, colostrum, urine,
and the secretions of the urogenital tract (Fig. 22.11; Table 22.2).

FIG. 22.11 Typical IgA levels in bovine body fluids. In other
species, milk and colostral IgA concentrations may be considerably
higher.

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