Effect of cadmium exposure on primary tumor growth and cell-mediated cytotoxicity in mice bearing MSB sarcomas.

In vivo MSB tumor growth and cell-mediated cytotoxicity (CMC) to MSB tumor cells in vitro were studied in male C57BL/6 mice exposed to 0, 3, 30, or 300 ppm Cd as CdCl2 in their drinking water for 21 weeks prior to and during tumor growth. CMC was assessed on days 5, 12, and 19 post injection with the use of both a 51Cr release assay and a 51Cr post-label assay. Cd exposure significantly inhibited the growth of MSB tumors in vivo and enhanced the levels of CMC in the tumor-bearing hosts. Peak levels of CMC on day 12 post tumor injection were significantly increased in Cd-exposed animals. However, whereas the inhibition of tumor growth was directly dependent on the dose of Cd, the enhancement of CMC was inversely related to dosage. These data suggested that other mechanisms in addition to increased CMC were involved in tumor growth inhibition. Possible factors such as direct inhibition of tumor growth by Cd and decreased serum blocking levels in Cd-exposed animals are discussed.

Further characterization of a low-molecular weight allergen fragment isolated from the green pea.

A low molecular weight allergen fragment present in the pea dialysate fraction was purified by ion-exchange chromatography and gel filtration. The highly purified allergen fragment inhibits both antigen-indiced passive cutaneous anaphlaxix reactions in guinea-pigs sensitized with rabbit anti-pea extract sera and Prausnitz-Küstner reactions in non-allergic volunteers sensitized with the sera of patients sensitive to green peas. Preliminary analysis of the purified allergen fragment indicates that it is a glycoprotein with a molecular weight of 1800 +/- 250.

The isolation of allergens from the green pea.

The aqueous extract of green peas was separated into 3 fractions (albumin, legumin, and vicilin) by dialysis against distilled water and isoelectric precipitation. The major antigenic and all of the allergenic activity of the pea extract was associated with the albumin fraction. The albumin fraction retains its allergenicity upon heating at 60 degrees C for 30 min or boiling at 100 degrees C for 5 min, but becomes partially inactivated by autoclaving at 120 degrees C for 15 min. The allergenic determinant expressed by the albumin fraction appears to be common to several other members of the legume family. In addition, the pea dialysate fraction was shown to specifically inhibit precipitin and passive cutaneous anaphylaxis (PCA) reactions involving rabbit antipea serum and the pea albumin fraction, and histamine release from passively sensitized monkey lung tissue using the serum of pea-sensitive patients.

Preliminary characterization of a major allergen of timothy grass pollen.

Previous studies with timothy pollen extracts demonstrated that a low molecular weight dialyzable fraction, antigen D, possessed the allergenic determinant of the major allergen of timothy pollen (allergen B). Bio-gel P-2 gel-filtration of the dialysate fraction resulted in the isolation of a fragment, antigen D3 with a molecular weight near 1000. The relationship of antigen D3 to the antigenic and allergenic determinants of allergen B was evaluated by passive cutaneous anaphylaxis (PCA) in guinea pigs sensitized with rabbit antitimothy sera and by allergen-induced histamine release from monkey lung tissue passively sensitized with the serum of timothy-sensitive patients. These studies demonstrated that 10 units of antigen D3 gave 1) a 70% inhibition of PCA reactions in guinea pigs challenged with allergen B, and 2) a 73% inhibition of allergen-induced histamine release from monkey lung tissue sensitized with timothy reagin and challenged with the crude pollen extract (WST). Although chemical characterization studies of the antigen D3 fragment are still being carried out it appears that the major components fo this fragment are 1) a flavonoid pigment - quercitin, 2) a disaccharide moiety - cellobiose, and 3) the amino acid threonine linked together in an )O-glycosidic type linkage.