R�sorption intestinale de la ferritine chez deux esp�ces animales aux possibilit�s d'absorption prot�ique n�onatale diff�rentes

143

100

The absorptive cell of the suckling rat ileum is specialized for the uptake and digestion of milk macromolecules from the intestinal lumen. The apical cytoplasm contains an extensive tubulocisternal system, a variety of vesicles and multivesicular bodies (MVB), and a giant phagolysosomal vacuole where digestion is completed. To determine if sorting of membrane-bound and fluid-phase macromolecules occurs in this elaborate endocytic system, we infused adsorptive and soluble tracers into ligated intestinal loops in vivo and examined their fates. Lysosomal compartments were identified by acid phosphatase histochemistry. Native ferritin and two ferritin-lectin conjugates that do not bind to ileal membranes (Con A, UE&) served as soluble tracers. Horseradish peroxidase binds to ileal membranes and thus was not useful as a fluid-phase tracer in this system. Cationized ferritin and a lectin that binds to terminal B-D-galactosyl sites on ileal membranes (Ricinus communis agglutinin[RCAdferritin) were used as tracer ligands. All tracers entered the wide apical invaginations of the luminal cell surface and were transported intracellularly. Membrane-bound tracers were found in coated pits and vesicles, and throughout the tubulocisternal system (where cationized ferritin is released from the membrane) and later, in large clear vesicles and MVB. In contrast, fluid-phase tracers appeared within 5 min in vesicles of various sizes and were not transported through the tubulocisternae; rather, they were concentrated in a separate population of vesicles of increasing size that contained amorphous dense material. Large clear vesicles, large dense vesicles, and MVB eventually fused with the giant supranuclear vacuole. Acid phosphatase activity was present in MVB and in the giant vacuole but was not present in most large vesicles or in the tubulocisternae. These results demonstrate that membrane-bound and soluble protein are transported to a common lysosomal destination via separate intracellutar routes involving several distinct prelysosomal compartments.Eucaryotic cells can incorporate extracellular macromolecules, both nonselectively (by fluid-phase endocytosis or pinocytosis) and selectively (by receptor-mediated or adsorptive endocytosis). In some cell types fluid-phase endocytosis seems to involve the formation of smooth membrane vesicles (32,36,41), whereas adsorptive endocytosis is invariably accomplished by the formation of vesicles from clathrin-coated membrane regions (2,3, 11,22,37). When the two processes are conducted by separate membrane microdomains on the cell surface, solutes and ligands are already sorted to a large degree before entering internal membrane systems. In many cell types, however, fluid-phase and adsorbed macromolecules may be taken up together and sorted in endosomal compartments (l, 2, 16, 22, 26, 27, 30, 37).Epithelial cells throughout the small intestine of neonatal rodents are highly specialized for endocytosis of luminal macromolecules. The membrane region involved in uptake is localized ...

Section: Resultssupporting

confidence: 87%

mentioning

confidence: 99%

Membrane-bound and fluid-phase macromolecules enter separate prelysosomal compartments in absorptive cells of suckling rat ileum.

Gonnella¹,

Neutra²

1984

143

100

“…It is most logical to conclude that uptake by these cells is entirely a nonselective process and is not associated with selective transport of antibodies. It should be emphasized that these results are by no means inconsistent with the observations in previous studies which well document the nonselective uptake of proteins by distal cells (Clark, 1959 ;Graney, 1965Graney, , 1968Kraehenbuhl et al ., 1967) . Considerable evidence for the lysosomal nature of the vacuoles in distal cells has suggested that this nonselective uptake reflects primarily a digestive function (Vacek, 1964 ;Cornell and Padykula, 1969) .…”

Section: Role Of Distal Epithelial Cellssupporting

confidence: 51%

“…Clark (1959) described a unique epithelial cell type in the lower jejunum and ileum of suckling rats which disappeared at an age when antibody transport ceased . Although a number of investigators (Clark, 1959 ;Kraehenbuhl et al ., 1967 ;Graney, 1965Graney, , 1968Kraehenbuhl and Campiche, 1969) have shown that these cells can concentrate a variety of tracers including antibodies, no clear evidence has been presented for selective binding or release of immunoglobulins from the cells . Nevertheless, it has been generally believed that these cells are responsible for transport of antibodies to the circulation (Clark, 1959 ;Anderson, 1963Anderson, , 1965Graney, 1965Graney, , 1968Bamford, 1966 ;Kraehenbuhl and Campiche, 1969) .…”

Section: Introductionmentioning

confidence: 99%

Intestinal Transport of Antibodies in the Newborn Rat

Rodewald

1973

325

162

Evidence has been reported that the proximal small intestine of the neonatal rat selectively transports antibodies into the circulation . This study describes the morphology of the absorptive epithelial cells in this region of the intestine and their transport of several immunoglobulin tracers : ferritin-conjugated immunoglobulins (IgG-Ft) and antiperoxidase antibodies . Cells exposed to rat IgG-Ft bound the tracer on the membrane of tubular invaginations of the apical cell surface . Tubular and coated vesicles within the cell also contained the tracer, as did the intercellular spaces . Uptake of tracer was highly selective and occurred only with rat or cow IgG-Ft ; when cells were exposed to chicken IgG-Ft, ferritin-conjugated bovine serum albumin, or free ferritin, tracer did not enter the cell or appear in the intercellular spaces . Experiments with rat and chicken antiperoxidase showed a similar selective uptake and transport of only the homologous antibody . When cells from the distal small intestine were exposed to the tracers, all tracers were absorbed nonselectively but none were released from the cells . Cells from the proximal small intestine of the 22-day-old rat failed to absorb even rat IgG-Ft . A model is presented for selective antibody transport in proximal cells of the neonatal rat in which antibodies are selectively absorbed at the apical cell surface by pinocytosis within tubular vesicles . The antibodies are then transferred to the intercellular space within coated vesicles . Distal cells function only to digest proteins nonselectively .

“…A vesicular and vacuolar apparatus develops after birth in the absorptive cells when they are in contact with colostrum or proteins (11,30,31,67,81,82) . Animals which have not been suckled show only few vacuoles (55) .…”

Section: J P Kraehenbuhl and M A Campichementioning

confidence: 99%

Early Stages of Intestinal Absorption of Specific Antibodies in the Newborn

Kraehenbuhl

Campiche

1969

Self Cite

145

In mammals, passive immunity is transferred from mother to offspring by transplacental passage or by intestinal absorption. The rabbit receives antibodies exclusively across the placenta, whereas intestinal absorption is the principal source of antibodies for the new-born pig. In the rat, passive immunity is transferred by both pathways. The role of the jejunal absorptive cells was investigated in these three species, by the use of specific immune globulins as tracers of protein absorption. Rabbit anti-peroxidase and anti-ferritin antibodies were injected into the jejunum of newborn pigs, rats, and rabbits, and absorption was studied over the first 2 hr. The specific antibodies were detected in glutaraldehyde-fixed tissues after in vitro treatment with the antigens, and in sera by immunological methods. Intact antibodies are transferred into the circulation of the pig and the rat, but not into that of the rabbit. In the three species, the jejunal absorptive cells take up antibodies by endocytosis. In the pig, the antibodies are transported across the epithelium in vacuoles. In the rabbit, the endocytosis of antibodies triggers a lysosomal response and all absorbed antibodies are trapped in lysosomes. In the rat, both situations are found; there is no evidence of transfer of antibody fragments into the circulation.