Low molecular weight Ia antigens in normal mouse serum: II. Demonstration of their T cell origin

A new procedure for analysing the relationship between different cell surface antigens

An immunoprecipitation-inhibition procedure is assessing whether different antigenic determinants are carried on the same molecule or on different molecules on cells. The procedure entails (a) exposing NP-40 lysates of cells to antibody against one antigenic specificity; (b) removing free antibody and immune complexes by absorption with protein A-bearing S. aureus bacteria; (c) adsorption of the NP-40 with a detergent binding resin; and (d) measuring the inhibitory activity of the lysates for antibody against another specificity by a rosetting assay. This method has several advantages over the widely used sequential immunoprecipitation procedure.

Regulation of IgE antibody production by serum molecules. VI: Preliminary biochemical and immunological characterization of serum molecules active in suppressing IgE antibody production

Molecules present in the serum and ascites fluids of low IgE responder mice previously inoculated with complete Freund's adjuvant have been analyzed in terms of certain biochemical and immunological characteristics. These studies demonstrate that the active molecules, termed "suppressive factors of allergy" (SFA), are (1) nondialyzable, (2) not associated with low-density or high-density lipoproteins, (3) heat stable, (4) precipitable by ammonium sulfate, and (5) approximately 150,000 daltons in molecular size. Studies with immunoadsorbents prepared from various antisera indicate that the suppressive molecules are (1) not immunoglobulin in nature, (2) not reactive with specific anti-H-2 alloantibodies, but (3) reactive with anti-beta 2m antibodies as well as (4) heterologous antisera raised against CFA-immune mouse serum.