THE ROLE OF THE THYMUS IN RESISTANCE TO INFECTION AND ENDOTOXIN TOXICITY.
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Biomedical subjects
Publications and source records attributed to S B SALVIN.
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Adult guinea pigs were made unresponsive to a heterologous protein (e.g. bovine gamma globulin, or BGG) or a hapten-protein conjugate (e.g. p-aminobenzoic acid-bovine gamma globulin, or PABAgammamiddot;BGG) by intraperitoneal injection of 80 mg cyclophosphamide and the specific antigen. This immunologic unresponsiveness developed to the specific antigen administered simultaneously with the cyclophosphamide, and not to any variants. Thus, animals unresponsive to PABAgammamiddot;BGG remained unresponsive to the original antigen on challenge with a variant, but formed delayed hypersensitivity and circulating antibody to the variant. The specificity of immunologic unresponsiveness, therefore, seems more closely related to the whole antigen molecule than does delayed hypersensitivity.
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"Gastric feeding" of adult guinea pigs with dinitrochlorobenzene (DCB) resulted in a specific unresponsiveness to sensitization with the specific contact hapten. The more DCB gastric-fed to a guinea pig, the more complete the unresponsiveness to the hapten. When mycobacteria were incorporated into the sensitizing emulsion, the state of unresponsiveness to the dinitrophenyl (DNP) group was less apparent. When animals gastric-fed with DCB were later sensitized with an in vitro conjugate of the hapten combined with a heterologous protein such as dinitrophenyl-hen egg albumin (DNP.HEA), an immune response similar to that in the controls occurred both to the hapten and to the protein carrier. However, when the tolerant animals were sensitized with a conjugate containing a homologous protein carrier such as dinitrophenyl guinea pig serum (DNP.GPS), they showed diminished immune responses in comparison with those in the non-tolerant controls. The presence of circulating anti-DNP antibodies from sensitization with DNP-HEA did not affect the unresponsiveness to the specific contact hapten, regardless of whether these antibodies are present before or after induction of tolerance. Sensitization with picryl chloride (PiCl) (a cross-reacting hapten), either before or after gastric feeding of DCB, did not affect the state of unresponsiveness to DNP. Similarly when the DNP-tolerant animal was sensitized with PiCl, the subsequent immune response was similar to that in the controls; cross-reactions with the DNP group both in the contact and circulating antibody phase occurred at a rate similar to that in the controls. The foregoing relationships can be explained by presuming that, upon the gastric feeding of DCB, an in vivo conjugate is formed with a somatic protein, which determines the basic specificity of the tolerance. Acquired tolerance seems to manifest an immunologic specificity similar to that of delayed hypersensitivity, a relationship not unexpected if delayed hypersensitivity is an early phase of the immune response.
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Neonatal guinea pigs during the first 2 weeks of life did not indicate the presence of delayed hypersensitivity intradermally, after sensitization with purified soluble antigens in dose levels that induced detectable delayed hypersensitivity in the skin of adults. Although Arthus type allergy was detectable in newborns, circulating antibody frequently preceded its appearance by several days. Passive Arthus reactions were not produced in newborns as readily as in adults. Contact hypersensitivity and allergic encephalomyelitis were induced in newborns, but corneal reactions were not. Total body irradiation with 200 r inhibited antibody formation in newborns, as in adults. In addition, the induction period for anamnestic responses in newborns and the antigen elimination rate were the same as in adults. Passive transfer of delayed hypersensitivity from sensitized newborns to normal adults was accomplished.
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Intradermal injection of a simple hapten (e.g., 1-fluoro-2,4-dinitrobenzene) in water-in-oil emulsion results in contact hypersensitivity to surface application of the homologous hapten and, after appearance of circulating antibody, in Arthus type hypersensitivity to a conjugate of homologous hapten with guinea pig serum. Intradermal administration of this conjugate induces delayed and subsequently Arthus hypersensitivity to the conjugate, but no evidence of a contact reaction to the hapten alone. When a conjugate of hapten plus solubilized guinea pig skin is used as the sensitizing antigen, both contact hypersensitivity to the hapten and delayed and/or Arthus reactions to the conjugate develop. These observations are consistent with the hypothesis that the specificity of contact sensitivity is directed toward some particular protein of the skin which has been modified by combination with hapten.
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Guinea pigs sensitized with either hen, duck, or goose egg albumin showed delayed hypersensitivity followed by Arthus reactions to the homologous antigen, but tended to have much weaker delayed responses and slower antibody formation to heterologous antigens. Guinea pigs with delayed hypersensitivity to one of the avian antigens had a slower antibody response to a secondary injection of heterologous antigen than to one of the homologous antigen. Sensitization with a protein conjugated with a hapten such as picryl chloride (Pi) or dinitrofluorobenzene (DFB) resulted in delayed hypersensitivity to the homologous conjugate, the homologous protein, and the homologous protein with a heterologous hapten. Circulating antibody and Arthus reactions occurred subsequently to the homologous conjugate, as well as to the homologous hapten attached to a heterologous protein. Delayed hypersensitivity thus seemed associated with the protein moiety, and Arthus responses with the hapten. Anamnestic responses followed injection of an antigen causing delayed hypersensitivity, but not of a hapten not causing delayed reactions. Thus, animals sensitized initially with Pi.HEA, DFB.HEA, or HEA produced antibodies sooner after a secondary injection of Pi.HEA than did unsensitized animals. No anamnestic response resulted when animals sensitized to Pi.BGG were injected with Pi.HEA. Thus, delayed hypersensitivity is indicated to be a preliminary and immature step in the immune process, with specificity directed against broad, more general features of the protein antigen. This intermediate step is followed by production of circulating antibody to any antigen having a similar basic structure, with the specificity of the antibody also directed against smaller immunologically active sites on the antigen molecule.
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The induction of delayed type of hypersensitivity to diphtheria toxoid in the guinea pig was not inhibited by total body irradiation up to 300 r in intensity. X-ray doses of 200 to 300 r administered about 18 hours before sensitization caused the period of delayed hypersensitivity to be extended to the 19th to 21st day postsensitization in. the absence of circulating antibody. X-ray doses of 50 to 100 r caused a decrease in the titer of circulating antibody, although delayed hypersensitivity lasted for a normal time. When 300 r irradiation was administered 18 hours after sensitization, delayed hypersensitivity lasted for the usual period and circulating antibody first appeared at the usual 13 to 14 days after sensitization. Introduction of normal serum or leucocytes into irradiated animals apparently did not reduce damage to the mechanism regulating the rate of antibody synthesis.
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Guinea pigs were injected in the footpads with either purified diphtheria toxoid or recrystallized egg albumin in Freund adjuvant without mycobacteria. Each guinea pig was then skin-tested only once with the specific antigen and bled for antibody determination. After injection of the sensitizing antigen, a latent period occurred during which neither sensitivity nor circulating antibody could be detected. A period of delayed sensitivity followed wherein circulating antibody could not be discerned and which could be transferred by lymph node cells. Ultimately, the Arthus type sensitivity developed, accompanied by circulating antibody. The duration and severity of reactions to homologous antigens during the last 2 phases varied with the antigen and with the dose. An increase in the sensitizing dose decreased the duration of the delayed type of allergy, a decrease in the dose prolonged the delayed type. Inclusion of mycobacterium in the sensitizing inoculum tended to introduce delayed sensitivity earlier and delay the onset of Arthus type sensitivity. When specific precipitate in antibody excess was included with the toxoid in the sensitizing dose, the onset of the Arthus phase was hastened. When lymph nodes from a large number of sensitized donors were removed during the latter part of the latent period, recipients of the cells showed a delayed type sensitivity.
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