Neutrophil Function In Vitro: Diapedesis and Phagocytosis

Abstract

The function of neutrophils within the mammary gland was modeled in vitro to include diapedesis and phagocytosis. The bovine mammary cell line, MAC-T3, provided a mammary epithelial monolayer for use as a biologically meaningful barrier to neutrophil diapedesis. Features included characteristic transepithelial resistance, tight junctional complexes, and polarity. Continuous readings of transepithelial resistance indicated a stable resistance over several hours. Staphylococcus aureus, at concentrations of 1 x 10(7) and 2 x 10(9) cfu/ml, did not appear to have any deleterious effects on monolayer integrity over short-term (1 to 2 h) exposure. Neither resting nor challenged neutrophils caused short-term damage to the monolayer. Transepithelial resistance of the monolayers remained unchanged even as neutrophils were actively migrating through the monolayer. Further work using the MAC-T3 cell line and electrical resistance to assess cell monolayer integrity could provide much insight into the mechanisms underlying degeneration of mammary epithelial cells. The ability of neutrophils to phagocytose foreign particles is important for protection of the mammary gland. Neutrophils from proven bulls varied in their rate and capacity of phagocytosis. Correlations between neutrophil function and production traits were negative and small. In vitro analysis of neutrophil function provides another tool for the study of natural mastitis resistance.

Characterization of transforming growth factor‐β growth regulatory effects and receptors on bovine mammary cells

“…Non-transfected mammary epithelial cells typically survive only 10-25 passages, whereas MAC-T cells (with the LT) have maintained growth and morphological properties after 350 passages (Huynh et al, 1991). Although oncogene "immortalization" may alter many cellular functions, MAC-T cells retain many properties of in vivo mammary epithelial cells, such as the presence of tight junctions, gap junctions, as well as the ability to differentiate (synthesis of caseins, lactose, and lipids) in response to prolactin and appropriate extracellular matrices (Huynh et al, 1991;MacDonald et al, 1994). Likewise, LT transfected mammary fibroblasts are growth ar-rested when cultured in the absence of appropriate hormonelgrowth factor stimulation.…”

Genetics of resistance to mastitis in dairy cattle

“…Immunity traits studied were mainly antibody response and functionality of neutrophils, which recruitment and activity are essential in the innate defence against udder infection [78,87]. Several authors [36,43,49] reported a significant sire effect of in vitro phagocytosis of blood neutrophils. Detilleux et al [19] found moderate heritabilities for migration (0.2 to 0.5) and phagocytosis (0.3-0.7) of neutrophils and for serum complement activity (0.4-0.5), using in vitro assays for 137 cows sampled three times around calving.…”

In vitro phagocytic activity of milk neutrophils during lactation cycle in Murrah buffaloes of different parity

“…Neutrophils travel from blood to the mammary gland in response to a variety of inflammatory mediators, such as cytokines, complement and prostaglandins (Janeway et al., 2001). The phagocyting ability of the in vitro analysis of neutrophil function provides a very effective tool for the study of natural mastitis resistance (MacDonald et al., 1994).…”