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Biomedical subjects

C W DeWitt

Publications and source records attributed to C W DeWitt.

At least 37 records · Page 2Linked to original sources
PubMed1976

Isolation and partial characterization of AgF-1:a rat lymphocyte membrane antigen.

A genetically defined, serologically identified antigen of the rat lymphocyte membrane (AgF-1) has been isolated. Viable spleen and lymph node cells, prepared by Ficoll-Hypaque density centrifugation from Fischer rats, were radioiodinated with soluble lactoperoxidase. Extracts obtained with Nonidet P-40 were shown to contain numerous radiolabeled proteins including cell-surface globulin. AgF-1 was isolated from these extracts by precipitation with a highly specific alloantibody in conjunction with xenospecific anti-globulin antibody and polyethylene glycol (PEG). The use of PEG greatly increased the efficiency of the double antibody technique. The putative antigenic peak was eluted from sodium dodecyl sulfate polyacrylamide gels (SDS-PAGE) and specific antigenic activity was recovered. Removal of the SDS from these eluates was achieved by equilibration with urea and passage over an anion exchange resin. Renaturation, as evidenced by specific inhibition of complement-mediated cytotoxicity, occurred upon the removal of urea by dialysis. The m.w. of the purified antigen was estimated to be 35 to 40,000 daltons by SDS-PAGE and was unaffected by reduction with 2-mercaptoethanol. Amino acid composition was roughly similar to those reported for the major histocompatibility antigens of the rat and other species.

Animals↗
PubMed1975

Ag-F: serological and genetic identification of a new locus in the rat governing lymphocyte membrane antigens.

A new genetic locus in the rat (Ag-F) is described. It controls expression of lymphocyte membrane antigens as determined by allospecific cytotoxic antibody. It is linked by approximately two recombination units to the gene for albinism and is therefore in linkage group I. It is suggested that Ag-F is the homologue in the rat of mouse H-1. It appears to be highly polymorphic and yields antigens which are highly cross reactive serologically. Disparity at Af-F is the probable cause of alloantibody responses attributable to reciprocal immunization between the Lewis and Fischer strains.

Absorption↗
PubMed1969

Mouse virulence of K(L) antigen-containing strains of Escherichia coli.

The mouse virulence of two K antigen-containing (L variety) strains of Escherichia coli (serotype O2:K1) isolated from human septicemia, and of their variants which lacked K antigen, was studied. The strains containing envelope antigen (K+) were highly virulent when injected intracerebrally or when suspended in mucin and injected intraperitoneally. After intraperitoneal injection of E-107 K+ (but not K-), there was a marked initial growth in the peritoneal cavity followed by bacteremia and infection of all the organs examined. In the mucin-enhanced lethal infection, this growth continued until death of the animal; in the nonlethal infection, growth ceased and the count dropped quickly after approximately 5 hr. Host defenses were depressed greatly by intraperitoneally, but not intravenously, administered mucin. Bacteria were most virulent when injected intraperitoneally. In vitro phagocytosis of the K+ bacteria required opsonins not needed for phagocytosis of the smooth K- variants. Opsonins were found in immunized rabbit and normal mouse sera. Immune rabbit sera contained antibodies with anti-K specificity which were opsonic in vitro and highly protective in vivo when administered passively. There appears to be a lesser anti-O opsonic and protective activity involving one of the strains (E-107 K+), and colonial morphology, agglutination, and absorption tests indicated a low amount of K antigen on this organism. No anti-O opsonic or protective activity could be shown involving the other strain (E-102 K+). When standard serological typing procedures were used, these two strains appeared to be identical serologically, but they differed greatly in sensitivity to immune rabbit serum in phagocytosis experiments in vitro.

Agglutination Tests↗