Immunoglobulin IgM detected by ELISA in bovine pituitary intraglandular colloid, non-vascular holocrine secretion of intermediate lobe cells.

ELISA was employed to determine the presence of immunoglobulin IgM in crude bovine pituitary intraglandular colloid (IGC). The percentage weight of IgM was 1.15% per total weight of lyophilized colloid. The colloid from 32 glands (sufficient amount to perform the ELISA) was pooled and placed in 20 ml cold phosphate buffered saline (pH 7.6) and lyophilized. The total weight of the lyophilized material was 2.05 g IGC, housed in the intraglandular lumen (residual lumen). This is the holocrine secretion of the marginal half of bovine pituitary intermediate lobe (IL) cells, known to produce the ACTH/LPH family of peptides. The discovery of immunoglobulin IgM in IGC is a unique phenomenon. Since it has been established that IL cells process common precursor molecules to different final secretory products, it can be envisioned that continuing studies will help to elucidate the relationship between immunoglobulins and the ACTH/LPH family of peptides.