John F. Finerty

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.

Induction of T cell activity in athymic (nu/nu) mice infected with Trypanosoma rhodesiense.

Infection of C57BL/10 (B10)3 nu/nu mice with Trypanosoma rhodesiense results in the development of significant T-cell reactivity in spleen and lymph nodes. The proliferative responses to mitogens, such as concanavalin A (Con A) and phytohemagglutinin (PHA), and in mixed-lymphocyte reactions (MLR) to alloantigens are enhanced compared with control uninfected nu/nu mice. These results serve to emphasize the stimulatory nature of trypanosomes on the immune system.

Cancer Vaccines: The Perspective of the Cancer Immunology Branch, NCI

The Cancer Immunology Branch, NCI, is supporting a great deal of exciting research relevant to cancer vaccine development. The few areas highlighted here are representative of ongoing research opportunities, but further progress depends largely on a continued infusion of investigator-initiated ideas to realize the potential of current research areas and open new ones.

Cancer Immunology: Highlights of the NCI Extramural Immunology Program

The long-term goal of research supported by the Immunology Program is to better understand immune mechanisms and their regulation in order to develop more effective strategies to strengthen the immune response against cancer. While there has been much progress in the field of immunology in recent years, many major questions remain unanswered. The role of MHC antigens in regulating the immune response to tumors is still unclear, as is the nature of putative tumor-associated antigens which are the targets of this response. The efficacy of various immune cell subsets in tumor cell killing is differentially affected by changes in tumor cell surface MHC antigen expression. Furthermore, although we now know much more about the cellular interactions in the immune response, little is actually known about the particular cell subsets which participate in an immune response is regressing versus progressing tumors. Interleukins have been shown to stimulate a variety of immunes response, and some of these immune modulators are now being tested in clinical trials, in various stages, to determine their antitumor effects. However, systemic administration of large quantities of interleukins can result in very different effects than those created by the local release of effector molecules from specific T-cell populations. Effector T cells can deliver lymphokines to precise target structures, whereas systemically administered lymphokines would affect preferentially those cells expressing the largest numbers of high affinity receptors for the lymphokines. The specificity of lymphokines as mediators of immunologic response rests largely or exclusively in the local release of such materials by T cells upon activation by antigen: MHC complexes on a stimulating cell. Because lymphokines show specificity only for nonantigen-specific, non-MHC-restricted receptor molecules on target cells, the effect of lymphokine injections is likely to be determined solely by the expression of these receptors. Thus, lymphokines function well as effector molecules in a number of specific immune reactions, but it remains to be determined whether they will be useful in regulating immune responses in specific disease situations. It may be critical to recruit specific immune cells to the area of tumor growth where they, in turn, can release lymphokines to activate appropriate antitumor effector cells. Adoptively transferred T cells of the helper phenotype can induce an effective antitumor immune response in recipient mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Tolerance to Type III Pneumococcal Polysaccharide in Monkeys

Rhesus and owl monkeys were injected intramuscularly with 10 to 10,000 γ of Type III pneumococcal polysaccharide. The monkeys were bled weekly, and then reinoculated with the polysaccharide at suitable intervals. The antibody content of their sera was measured by radioimmunoassay and the antigen content of selected sera estimated by the inhibitory effect of the serum upon the capacity of rabbit antisera to precipitate the polysaccharide. Ten γ of the polyeaccharide immunized the monkeys. Ten thousand γ did not immunize them but instead reduced their serum antibody to very low levels. One thousand γ also reduced their serum antibody to very low levels, but not uniformly as far as 10,000 γ. These findings indicate that 1,000 to 10,000 γ of this polysaccharide appear to cause immunologic tolerance in primates.

Disk electrophoretic separation of soluble preparations of Plasmodium lophurae and Anaplasma marginale.

Soluble preparations of Plasmodium lophurae and Anaplasma marginale were prepared by ultrasonic disruption of the cell-free parasites. Zone electrophoresis in acrylamide gel demonstrated a minimum of 12 fractions for both preparations. The advantages of this electrophoretic method for the study of constituents of these organisms are discussed. Previous reports which dealt with the electrophoretic separation of plasmodial and Anaplasma preparations have employed paper, agar, starch, and acrylamide gel as the supporting media (Sherman and Hull, 1960; Ristic and Mann, 1963; Sherman, 1964; Sodeman and Meuwissen, 1966). Sherman (1964) reported four to six components from a soluble preparation of Plasmodium lophurae employing immunoelectrophoresis and eight fractions with starch gel electrophoresis. Ristic and Mann (1963) demonstrated two components of Anaplasma marginale also by immunoelectrophoresis. This report presents data obtained when sonicated preparations of P. lophurae and A. marginale were analyzed by disk electrophoresis (Davis, 1964). The method was found to be superior for analyzing soluble preparations of P. lophurae and A. marginale. MATERIALS AND METHODS The strain of P. lophurae employed was obtained from Dr. William H. Trager, Rockefeller University, New York. Methods for the maintenance and preparation of cell-free suspensions of this parasite have been previously described (Wallace et al., 1965). The strain of A. marginale employed was maintained in calves as described by Dimopoullos and Bedell (1962). Calves with parasitemias greater than 50% as determined by Giemsa-stained smears were exsanguinated and the blood collected in heparin sodium solutions (1,000 USP units per ml) at a concentration of 0.3 ml per 50 ml blood. Cell-free suspensions of A. marginale were prepared according to Figure 1. Ultrasonic disruption was carried out for 60 sec at 8 amp with a BranReceived for publication 25 August 1967. * Supported in part by Public Health Service Research Grant AI-02250 and Graduate Training Grant AI-00184 from the NIAID. t Present address: Laboratory of Germfree Animal Research, NIH, Bethesda, Maryland 20014. son sonifier (Branson Instruments, Inc., Stamford, Connecticut). The cell-free parasites were centrifuged at 10,000 g for 10 min at 4 C, resuspended in saline (v/v), and sonicated at 8 amp for 60 sec, in an ice bath, with a Branson sonifier. The preparations were centrifuged at 50,000 g for 20 min at 4 C and the sediment discarded. Supernatant fluids were stored at -20 C until used. P. lophurae extracts were freeze-dried before storing at -20 C. Disk electrophoresis was performed according to Davis (1964) utilizing a current of 4 ma per tube for separation. Length of migration was determined by observation of a dye front after which the gels were fixed in 7.5% acetic acid containing 1% Amido Black. The gels were destained as previously described (Davis, 1964) and stored in 7.5% acetic acid.