Enzymatic and immunochemical properties of lysozyme--restriction of recognition of lysozyme antigenic determinants in pigs

Polyclonal antibodies to human milk caseins

Preparations of total human casein and its individual fractions were isolated for production of specific polyclonal antibodies. Immunization procedures used differed in the schedule for antigen administration, antigen concentrations, degree of additional purification, and modification of the size of molecules. Immunoprecipitation techniques failed to provide an unambiguous proof of the presence of antibodies to human milk caseins in antisera even after immunization of animals phylogenetically considerably different from man. Immunoblotting, however, allowed antibodies to beta-casein to be identified and compared with available monoclonal antibodies.

Schistosoma mansoni: chemical stabilization of cercariae by aldehydes

Chemically stabilized cercariae of Schistosoma mansoni have been developed by inactivating surface glycoproteins which are essential for their survival. The inactivation was achieved by reaction with 0.01-0.1% glutaraldehyde, 0.1-1% formaldehyde, and 0.37-3.7 microliters citraconic anhydride. The cercariae lost their viability but retained the ability to exclude trypan blue for up to 2 years in a manner similar to live cercariae and in contrast to cercariae killed by other means, which took up the dye immediately. The chemically stabilized cercariae reacted with polyclonal and monoclonal antischistosome antibodies in an indirect immunofluorescence assay for up to 2 years, indicating the retention and preservation of surface antigens. Chemically stabilized cercariae revealed the presence of antischistosome antibodies as early as 1 week after infection when used for immunodiagnosis of mouse and rat infections. The presence of Fc receptors for human IgG on the stabilized cercariae interfered in their use as an immunodiagnostic reagent of human schistosomiasis. The stabilized cercariae were also used to screen cultures for monoclonal antischistosome antibodies. Preliminary results indicated that immunization of mice with glutaraldehyde stabilized cercariae imparted protective immunity to mice.

Comparative studies on radiolabeling of lysozyme by iodination and reductive methylation

Before attempting to radiolabel proteins it is essential that conditions be found for optimal reaction by use of cold reagents. Iodination by the chloramine-T method was not suitable for radiolabeling of lysozyme as it resulted in reduced solubility, large conformational changes, loss of enzymic activity and a decrease in immunochemical reactivity. On the other hand, reductive methylation of lysozyme by formaldehyde and sodium cyanoborohydride was considered suitable for radiolabeling of lysozyme. The extent of reaction with the free amino groups was dependent on the concentration of lysozyme and the molar ratios of the reactants (lysozyme, NaCNBH3 and HCHO). The molecular weight, net charge and enzymic activity of the lysozyme derivatives were similar to the native molecule. The immunochemical reactivity was reduced by 6-13% when more than 6 amino groups were modified. Reductively methylated rabbit IgG showed unaltered molecular weight, net charge and very little conformational changes compared to native IgG. Partial reaction, by reductive methylation using [14C]HCHO, lysozyme with specific activity of 11.1 X 10(6) cpm/mg protein and pig anti lysozyme antibody with specific activity of 2.95 X 10(5) cpm/mg protein were prepared.