Charles B. Evans

A MICROSCOPIC STUDY OF TETRACYCLINE LOCALIZATION IN SKELETAL NEOPLASMS

to indlicate that antibiotics of tlte tetracycline series localize in the skeleton, and apparently specifically in regions of newly proliferated bone (Fig. 1, 2). It has also l)cen show-n that tlte fluorophor in bone is, in all probability, chemicallv unaltered tetracycline (22) w-hich retains its antimicrobial activity (1, 4). The fluorescent (oml)oun(l appears to l)e colflplctely bound to a material dialyzable from acid extracts of fluoresdent botie and to l)e rentoved by ethylenediamjnetetracetic acid! at about neutral 1)11. Since it would appear that the tetracyclines thus afford a convettient indlex at the histological level of ant apparentl rather specific physiological

Immunoglobulin isotype distribution of malaria-specific antibodies produced during infection with Plasmodium chabaudi adami and Plasmodium yoelii

The antibody response of mice to Plasmodium chabaudi adami and Plasmodium yoelii has been compared using a solid phase isotype-specific radioimmunoassay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Serological cross-reactivity between these parasites was substantial. Studies using a radioimmunoassay detecting all classes of malaria-specific antibody demonstrated that during the early part of infection it was not possible to distinguish between homologous and heterologous reactions. Immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that 50% or more of the protein antigens detected were apparently shared by both parasites although the intensity of bands was always greater with homologous reactions. However, the distribution of isotypes in the antibody (Ab) response differed in the two infections. P. chabaudi infections were characterized by a predominant and persistent IgM response, moderate IgG2 and IgG3 and little significant IgG1 response during a primary infection. By contrast, IgM antibodies were transient in P. yoelii infection, IgG2 was the predominant isotype, and both IgG1 and IgG3 antibodies were present during a primary infection. These differences in isotypes were also detected when sera were tested on the heterologous antigen extracts suggesting that antigens shared by P. chabaudi and P. yoelii do not necessarily induce similar antibody responses in the two infections.

Plasmodium berghei and Eperythrozoon coccoides: Antibody and immunoglobulin synthesis in germfree and and conventional mice simultaneously infected

Abstract The immune response to Eperythrozoon coccoides and the malaria parasite Plasmodium berghei was evaluated in germfree (GF) and conventionally reared (CV) mice infected with both parasites. Following infection, the mice showed significant changes in the levels of the immunoglobulins IgM, 7Sγin1, 7Sγ2a, and 7Sγ2b, but no detectable changes in IgA. Increases in immunoglobulin levels were first observed in GF mice, but by the twelth day both GF and CV mice had comparable levels. 7Sγ2a globulin had a bimodal distribution in both groups of mice which probably was due to heterogeneity in the allotype of this immunoglobulin. IgM levels closely paralleled the antibody responses to P. berghei suggesting that most of the antibody to this parasite was IgM. Relatively low levels of antibody to both parasites, in comparison to the large immunoglobulin response, were detected in GF and CV mice. The possible causes for the low titers are discussed.

Plasmodium yoelii: comparison of indirect immunofluorescence and radioimmunoassay for detecting monoclonal antibodies to malaria.

Abstract The techniques of indirect immunofluorescence (IFA) and radioimmunoassay (RIA) were compared for efficiency in detecting antimalarial monoclonal antibodies in culture supernatants following lymphocyte hybridization. Culture supernatants from 479 wells were examined. Approximately 9% of the wells were found to contain antibodies to Plasmodium yoelii by IFA and 13% by RIA analysis. However, only 4.6% of the wells were positive by both IFA and RIA techniques. In general, stage-specific hybrids were more easily detected in IFA than RIA tests, whereas monoclonal antibodies binding to non-stage-specific antigens were more readily detected by RIA than IFA analysis. Selected monoclonal antibodies of the IgG and IgM classes were purified by protein A and molecular-weight-exclusion chromatography, respectively. The minimal amount of monoclonal antibody required to give a positive IFA reaction ranged from 1.6 to 100 μg antibody/ml (0.03-2 μg antibody/test), but only 0.1 to 100/μ.g antibody/ml (1 ng-2 μg antibody/test) was needed to produce a positive RIA reaction. Use of an isotype-specific RIA for screening for antimalarial antibodies resulted in the detection of additional hybridomas missed by standard IFA and RIA tests. Thus, it is important to use several serologic methods if maximal efficiency in detecting antimalarial monoclonal antibodies is to be achieved.