Immunology 1996 87 198-204

T-cell-receptor dose and the time of treatment during murine retrovirusinfection for maintenance of immune function

B. LIANG,* S. ARDESTANI,* J. J. MARCHALONISt & R. R. WATSON* *Department of Family andCommunity Medicine, tDepartment of Microbiology and Immunology, University of Arizona, Tucson, AZ, USA

SUMMARY

C57BL/6 mice were injected with different doses of human T-cell receptor (TCR) V/8.1 CDR1peptide at different times after murine retrovirus (LP-BM5) infection. Injection with TCR V/8.1CDR1 peptide largely prevented the retrovirus-induced reduction in B- and T-cell proliferation,and T-helper (Thl) cytokines [interleukin-2 (IL-2) and interferon-y (IFN-y)] secretion. It alsosuppressed T-helper 2 (Th2) cytokines (IL-6 and IL-10) production, which was stimulated byretrovirus infection. These effects were accomplished using at least 100 ,ug of peptide per mouse andthe most effective dose of peptide had to be given within 4 weeks after retrovirus infection.Immunization with doses above 100 ,ug/mouse as long as 4 weeks postinfection maintained naturalkiller (NK) cell activity during retrovirus infection. Reducing the dose of peptide or delaying ituntil the disease progressed towards early murine acquired immune deficiency syndrome (AIDS)allowed development of immune dysfunction. These studies provide data suggesting that immunedysfunction, induced by murine retrovirus infection, was largely prevented by TCR V/I CDR1peptide injection.

INTRODUCTION

Acquired immune deficiency syndrome (AIDS) is a disease ofretroviral etiology, characterized by immune dysfunction,opportunistic infections, and eventually death. Murine acquiredimmune deficiency syndrome (MAIDS), induced by infectionwith murine LP-BM5 leukemia retrovirus (MuLV) mixture, isstrikingly similar to that of human AIDS, even though humanimmunodeficiency virus (HIV) and murine LP-BM5 MuLVrepresent different types of retrovirus.1

LP-BM5 MuLV infection causes splenomegaly, lymphade-nopathy, hyper-y-globulinemia, B-cell hyperactivity at the earlystage of retrovirus infection, and progressive defects in T- andB-cell functions leading to loss of host resistance to pathogensand neoplasia.1 Aberrant cytokine production because ofretrovirus infection, caused by a switch from T-helper 1 (Thl)cell response to a T-helper 2 (Th2) cell response, promotesprogression to AIDS.2 In HIV+ patients and MuLV-infectedmice, T-cell proliferation and Th l cytokine [interleukin-2(IL-2) and interferon-y (IFN-y)] production decline while Th2cytokine (IL-4, IL-5, IL-6 and IL- 10) and immunoglobulinproduction increase. 6 The Th 1 to Th2 cell conversion maydetermine the fatal outcome of the disease as part of themechanism producing severe immunodeficiency and loss ofdisease resistance. When IL-4-deficient (IL-4 gene knockout)

Received 7 July 1995; revised 31 August 1995; accepted 27September 1995.

Correspondence: Dr Ronald R. Watson, Department of Family andCommunity Medicine, University of Arizona, Tucson, AZ 85724, USA.

mice, which are defective in Th2 cytokine responses, wereinfected with LP-BM5 retrovirus, there was no lethality anddevelopment of T-cell abnormalities was delayed.7 Adminis-tration of anti-IL-4 monoclonal antibody (mAb) to LP-BM5retrovirus-infected mice also normalized the imbalance of Thland Th2 responses induced by retrovirus infection, preventedretrovirus-induced suppression of immune responses, andalleviated the typical symptoms of murine AIDS: hyper-y-globulinemia and splenomegaly.7

Autoantibodies (AAbs) binding a peptide determinantcorresponding to the CDR1 of the T-cell receptor (TCR) VBdomain were elevated during murine retrovirus infection.8 Theelevation of the levels of these AAbs is an early event followingretroviral infection which corresponds in part to the generalpolyclonal activation of the B cells with selectivity for particularV/I sequences occurring later. The production of high levels ofanti-TCR AAbs early in this disease with continued productionof some AAbs suggests that they might be involved in modulationof immune responses caused by retrovirus infection. The AAbsdirected against CDRI determinants can be considered naturalantibodies against public or regulatory idiotypes9"0 since thisregion is the least variable of the CDRs and is completelyspecified by the V/B gene sequence. Immunization with a TCRV/B peptide identified by these AAbs slowed the progression ofthe loss of B-cell mitogenesis."1 Preferential expansion of someTCRoc, CD4+ T cells induced by retroviral superantigens inboth human and murine retrovirus infection is an importantimmunopathogenic mechanism.' 2-15 Selective expansion/dele-tion of some TCRxB CD4 + T cells may lead to polyclonal

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Effects of TCR peptide immunization

activation of T and B cells at an early stage, and subsequentaberrant cytokine production. Eventually these abnormalitieslead to profound immunodeficiency with immunosuppressionof cell-mediated immunity. The current studies were designedto characterize the role of the TCR peptide in preventingretrovirus-induced immune dysfunction. We determined whetherthere was a dose-response relationship of the TCR V/I8.1CDRl peptide and T-cell responses, and if injection late in theLP-BM5 retrovirus infection would prevent or restore theretrovirus-induced suppression of the immune response, alleviatehyper-y-globulinemia, and normalize cytokine secretion bysplenocytes.

METHODS AND MATERIALS

Animals and murine AIDSFemale C57BL/6 mice, 4-weeks old, were obtained from theCharles River Laboratories Inc. (Wilmington, DE). Animalswere cared for as required by the University of ArizonaCommittee on Animal Research. After 2 weeks housing in theanimal facility in the Arizona Health Science Center (Tucson,AZ), they were randomly assigned to one of the followingtreatments with 8 mice per group for study A: uninfected,normal mice; uninfected, normal mice infected with saline(pyrogen free); LP-BM5-infected mice infected with 5 pg TCRVA CDRl peptide; LP-BM5-infected mice injected with 25 pgTCR V/I CDRl peptide; LP-BM5-infected mice injected with100 pg TCR V/I CDRl peptide; LP-BM5-infected mice injectedwith 200 pg TCR V/I CDRl peptide; LP-BM5-infected miceinjected with 500 pg TCR V/I CDRl peptide; LP-BM5-infectedmice injected with saline and 200pg Poly AU adjuvant; LP-BM5-infected mice injected with 25 pg TCR V/I CDRl peptideand 230 pg Poly AU adjuvant; LP-BM5-infected mice injectedwith saline and 230,pg Ribi MPL TDM CWS adjuvant; LP-BM5-infected mice injected with 5 pg TCR V/I CDR1 peptideand 230 pg Ribi MPL TDM CWS adjuvant; LP-BM5-infectedmice injected with 25 pg TCR V/I CDR1 peptide and 230 RibiMPL TDM CWS adjuvant. LP-BM5 retrovirus was adminis-tered intraperitoneally to mice in 0 I ml saline with an esotropictitre (XC) of 4-5 log,0 plaque-forming units (PFU)/ml, whichinduces disease with a time course comparable to that previouslypublished.' Administration of peptides (dissolved in saline) andadjuvants were performed 2 weeks after LP-BM5 infection.Uninfected, normal mice were injected with complete culturemedium used for LP-BM5 virus growth as controls. Infectionof adult female C57BL/6 mice with LP-BM5 MuLV leads to therapid induction of clinical symptoms with virtually no latentphase. For study B, the treatment were: LP-BM5-infected miceinjected with saline 2 weeks after infection; LP-BM5-infectedmice injected with 200 pg TCR V/I CDR1 peptide 2 weeks afterinfection; LP-BM5-infected mice injected with 200 pg TCR V/ICDR1 peptide 4 weeks after infection; LP-BM5-infected miceinjected with 200 TCR V/I CDR1 peptide 6 weeks afterinfection; LP-BM5-infected mice injected with 200 pg TCR V/BCDR1 peptide 8 weeks after infection; LP-BM5-infected miceinjected with 200 pg TCR V/I CDR1 peptide 10 weeks afterinfection.

PeptidesA set of overlapping 16-mer peptides that duplicate covalentstructure of the V/ID/IJ/IC/I protein'016 predicted from a

human TCR-/I gene sequence'7 has been produced. TCR V/ICDRI hasasequence,CKPISGHNSLFWYRQT,thatcorresponds to the completed CDR1 and N-terminal fiveresidues of Fr2'0" 8 of the human V#8.1 gene product.'7Normal polyclonal IgG pools contain natural AAbs againstpeptide segments corresponding to CDR1, Fr3 and to aconstant region 'loop' peptide.'0 Unimmunized mice also havenatural IgG antibodies directed against the same peptidesegments; in particular, there is strong reactivity to the humanCDR1 test peptides. A computer comparison of human andmurine V/ sequences (J. J. Marchalonis, unpublished analysis)using the progressive alignment algorithm of Feng & Doo-little'9 showed that certain human and murine V/I sequencescould be grouped into families; e.g. human V#6 and V/I8correspond to murine C#Il and human and murine V/I5 are inthe same clusters.

Standard cytokines and their antibodiesRat anti-murine IFN-y, IL-2-, IL-6-, IL-10-purified antibodies,rat anti-murine IFN-y, IL-2-, IL-6-, IL-10-biotinulated anti-bodies, and recombinant murine IFN-y, IL-2, IL-6, IL-10 wereobtained from Pharmingen (San Diego, CA).

Enzyme-linked immunosorbent assay (ELISA) for cytokinesIFN-y, IL-2, IL-6 and IL-10 were produced by splenocytes asdescribed previously.20 Briefly, spleens were gently teased withforceps in culture medium [RPMI-1640 containing 10% fetalcalf serum (FCS), 2mm glutamine, 100 U/ml penicillin andstreptomycin, complete medium (CM)], producing a single-cellsuspension of spleen cells. Red blood cells were lysed by theaddition of a lysis buffer 0-16 M ammonia chloride Tris buffer,pH 72) at 370 for 3 min. Then the cells were washed twicewith CM. Cell concentration was counted and adjusted to1 x 107 cells/ml. Splenocyte viability was more than 95% asdetermined by trypan blue exclusion. 0-1 ml/well of splenocytes(1 x 107cell/ml) from were cultured in triplicate on 96-well flat-bottom culture plates (Falcon 3072, Lincoln Park, NJ) withCM. Splenocytes were then stimulated with concanavalin A[Con A, 1O pg/ml, 0-1 ml/well (Sigma)] for induction of IL-2and IL-10 with 24-hr incubation, IFN-y with 72-hr incubationat 37°, 5% CO2 incubator. Splenocytes were also stimulated bylipopolysaccharide (LPS, g/ml, Gibco, Grand Island, NY)for 24-hr induction for IL-6 production. After incubation, theplates were centrifuged for Omin at 800g. Supernatant fluidswere collected and stored at -700 until analysis. They were

determined by sandwich ELISA as described previously.20

Mitogenesis of splenocytesSplenic T- and B-cell proliferation was determined by [3H]-thymidine incorporation as described previously.20 Briefly,splenocytes in 0 1 ml of CM (1 x 107cell/ml) were cultured in96-well flat-bottom cultured plates (Falcon) with Con A andLPS (10 pg/ml). They were incubated at 370, 5% CO2 incubatorfor 20 hr for Con A-induced T-cell proliferation and 44hr forLPS-induced B-cell proliferation, and then pulsed with [3H]-thymidine (0-5 pCi/well, New England Nuclear, Boston, MA).After 4 hr they were harvested by a cell-sample harvester(Cambridge Technology, Cambridge, MA). Radioactivity was

determined by a liquid scintillation counter (Tri-Carb, 2200CA, Packard, Lagunahills, CA). Data were presented as countsper minute (c.p.m.).

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Natural killer (NK) cell cytotoxicityNK cell function was measured by a fluorescent-concentration-release assay modified from the method of Wierda et al.21Briefly, this method measures the fluorescent dye-2,7'-bis-(carbosyethyl)-5,6'-carboxyfluorescein (BCECF) (MolecularProbes, Eugene, OR) remaining in the target cells using thePandex Fluorescence Concentration and Analyzer (FCA)(IDEX, Portland, ME). YAC-1 target cells were washed oncewith PBS and labelled with the carboxyfluorescein derivative.Effector to target (E: T) ratios were adjusted to 100: 1 and50: 1, and plated in U-bottom microtitre plates (Falcon 3077,Lincoln Park, NJ) containing 4 x 104 target cells/l00 pl. Theplate was centrifuged (90g) for 3 min to facilitate cell-to-cellinteraction. The cells were then incubated at 370 in a humidifiedatmosphere of 5% CO2 for 3 hr. After incubation, 20 MI of 1%inert fluoricon polystyrene assay particles was added to eachwell of plate (Pandex Harvesting Plate, IDEX), and 80 y1aliquot from each well of irradiation plate was transferred to aPantex plate. Epifluorescence of each well in the harvest platewas automatically read at 485/533 nm excitation/emissionwavelengths for BCECF using the Pantex FCA. Specificcytotoxicity (%) was calculated as follows:

Spontaneous release - experimental fluorescenceSpontaneous release - maximum release x 100.

StatisticsThe statistic tests for comparison among groups were finishedin NCSS program (Kaysville, UT) using Friedman's Block/Treatment test, followed by Duncan's Multiple Range Testbetween any two groups. P < 0-05 was considered a significantdifference between two groups.

RESULTS

Body weight

There was no change in food consumption because of infectionor injection (data not shown). The body weight of the mice wasnot affected by various levels of TCR VJ3 CDR1 peptideinjection or time course of injection postinfection. The spleenand lymph node weights were significantly (P < 0 05) elevatedin the infected mice (Figs la and b), which indicated thatinfection had progressed to murine AIDS.

Mitogenesis of splenocytesProliferation of Con A- and LPS-induced splenocytes was sig-nificantly decreased (P < 0 05) by murine retrovirus infection(Figs 2, 3a and b). Suppression of T- and B-cell proliferation inthe spleen, induced by retrovirus infection, was significantly(P < 0-05) prevented by TCR VB CDR1 peptide injection.Peptide dosages above 200 ,g/mouse (Fig. 2) and injectionbefore 4 weeks postinfection (Fig. 3) maintained near normalT- and B-cell proliferation which were significantly (P < 0 05)higher than that in infected, unimmunized mice. Injection withless than 200 pg/mouse of peptide (Fig. 2) or at 6-10-weekspostinfection (Fig. 3), did not prevent development ofdecreased, in vitro proliferation of mitogen-stimulated T andB cells.

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Figure 1. Spleen and lymph node weight. The spleen and lymph nodeweights were significantly (P < 0-05) elevated in the infected mice, butTCR peptide immunization had no significant effect on the spleen andlymph node weights.

Nature killer (NK) cell cytotoxicity

Murine retrovirus infection significantly (P < 0-05) reduced thesplenic NK cell activity, which was largely (P < 0-05) main-tained in infected mice injection with the TCR VB CDR1peptide (Figs 4a and b). Peptide dosages above 100 pg/mouse(Fig. 4) and injection by 4 weeks postinfection (Fig. 4b)maintained near-normal NK cell activity which was signifi-cantly (P < 0-05) higher than that in infected, unimmunizedmice. Injection with less than 100 ,ug/mouse (Fig. 4a) at or after6-weeks postinfection (Fig. 4) permitted development of asignificantly decreased NK cell cytotoxicity.

Cytokine production of splenocytes

In vitro production of Thl cytokines, IL-2 (data not shown)and IFN-y by Con A-stimulated splenocytes was significantly(P < 0-05) inhibited in the retrovirus-infected mice (Fig. 5).TCR V# CDR1 peptide injection significantly (P < 0-05)normalized IL-2 (data not shown) and IFN-y release bymitogen-stimulated splenocytes compared with infected, unim-munized mice (Fig. 5). Injection with 200 ,ug/mouse or higher

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Figure 2. Con A-stimulated splenocyte proliferation. Retrovirusinfection significantly (P < 0 05) suppressed T-cell proliferation. TCRpeptide immunization at doses at or above 200 jig/mouse significantly(P < 0-05) prevented the suppression of T-cell proliferation in murineAIDS.

© 1996 Blackwell Science Ltd, Immunology, 87, 198-204

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dose of peptide (Fig. 5) and before 6-weeks postinfection(Fig. 5) maintained near-normal ThI cytokine productionwhich were significantly (P < 0-05) higher than that in infected,unimmunized mice. Injection at dosages of less than 200 yg/mouse (Fig. 5) or after 6-weeks postinfection (Fig. 5) hadsignificantly (P < 0-05) decreased Thl cytokine production.

Release of Th2 cytokines, IL-6 (data not shown) and IL-10

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in vitro by mitogen-stimulated spleen cells, was significantly(P < 0 05) increased in the retrovirus-infected mice (Fig. 6).TCR VB CDR1 peptide injection significantly (P < 0-05)normalized IL-6 (data not shown) and IL-10 release bymitogen-stimulated splenocytes (Fig. 6). Immunization withTCR peptide above 100 Mg/mouse (Fig. 6) and 4-weekspostinfection (Fig. 6) maintained near-normal Th2 cytokineproduction which was significantly (P < 0-05) lower than thatof infected, unimmunized mice. Injection at dosages of less than100 pg/mouse (Fig. 6) or after 4-weeks postinfection (Fig. 6)permitted development of a significantly (P < 0-05) increasedTh2 cytokine production.

Influence of adjuvants on TCR immunization

The adjuvants used generally had no significant (P > 0-05)effect on maintaining the immune function (Fig. 7).

DISCUSSION

TCR peptide therapy was initially developed in the Lewis ratexperimental autoimmune encephalomyelitis (EAE) model andsubsequently was shown to be effective in chronic relapsingEAE in mice, which models multiple sclerosis (MS) clinicallyand pathologically.2>27 For the therapy to work, animalsmust be successfully immunized with disease-associated TCR

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Figure 5. Interferon-y production of splenocyte. Retrovirus infectionsignificantly (P < 0-05) suppressed IFN-y production. TCR peptideimmunization at doses at or above 200jpg/mouse, or before 6 weekspostinfection, significantly (P < 0-05) normalized IFN-y production.

1996 Blackwell Science Ltd, Immunology, 87, 198-204

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V-region peptides. Immunization induces TCR peptide-specificCD4 + and CD8 + T cells and antibodies, and the passivetransfer of either peptide-specific T cells or Ab is sufficient tosuppress MS disease.22 24'28 It has been hypothesized that TCRpeptide immunization stimulates a natural immunoregulatorynetwork that induces tolerance of T cells expressing thetargeted TCR V gene product.24

In the present study, injection with a TCR V/I CDR1peptide significantly prevented murine retrovirus-inducedimmune dysfunction, and normalized cytokine production.This change occurred simultaneously with restoration of tissuevitamin E, a mild immunostimulant and reduced lipidperoxidation in tissues, which decreased the oxidative stresscaused by free radical products, i.e. lipid fluorescence and dieneconjugates. The concentrations of hepatic and cardiac vitaminE were significantly (P < 0-05) reduced by retrovirus infec-tion,29 while TCR V/I CDR1 peptide immunization, at dosagesof above 200,g/mouse and 4-weeks postinfection, significantly(P < 0-05) maintained hepatic and cardiac vitamin E levels ator near those of uninfected mice.29 Retrovirus infectionsignificantly (P < 0-05) increased hepatic and cardiac lipidperoxidation that produced more free radical products, i.e.lipid fluorescence and diene conjugates.29 TCR V/I CDR1peptide immunization, at dosages of 100-500,ug/mouse and4-weeks postinfection, significantly (P < 005) reduced thehepatic and cardiac-free radical products.29

Injection early or with a significant amount of TCRantigen was necessary to prevent immune dysfunction. Clearlyinjection early in the infection, prior to significant immunedysfunction, was critical. However the addition of adjuvanthad a variable effect expanding the efficacy of very low(otherwise ineffective) doses of TCR antigen. These resultsindicate that TCR V/I CDR1 peptide functions as animmunoregulatory element in the complex networks ofinteractions among the components of the immune systemand anti-oxidation system. They provide an insight into thepathogenesis during progression to AIDS, as well as into themechanisms of idiotypic networks murine. These results alsoexpand understanding of the roles of vitamin E and freeradical products on regulation of immune function duringmurine retrovirus infection, which support the concept thatcombination of immune therapy and vitamin E supplementa-tion therapy for murine retrovirus infection may be moreefficacious than either alone.

Most antigens are recognized through their interactionwith the variable portions of the TCR-cx and -/I chains.However, T cells recognize superantigens on the basis of theirexpressed V/ region alone, independently from the othervariable TCR segments. Progression of CD4+ T-cell deple-tion/expansion may require cycles of mutation in the retro-viral superantigen genes, resulting over time in the eliminationof CD4+ T-cell-bearing V/Is.'5 AAbs to TCR V/ induced byimmunization of TCR V/I CDR1 may slow the selectivedeletion/expansion of some T cells bearing specific V/I bycytolysis or other inhibitory mechanisms, i.e. obstruction ofsuperantigens binding to specific TCR V/ chains by AAbsbinding to V/I chains. In retrovirus-infected mice AAbs toTCR V/I CDR1 in the serum were increased by administrationofTCR V/ CDR1 peptide, but not to the control peptide. Theincreased production of AAbs to TCR V/ in retrovirus-infected mice without TCR V/ CDR1 peptide administration

may not be enough to alter the profile of expansion/deletion ofT-cells bearing specific TCR V/ induced by retroviral super-antigens. However, it is unclear why the TCR V/I CDR1peptide induced selective alteration of T-cell expansionbearing specific V/ in the infected mice. It was possiblycaused by a difference in the affinity of the different V/I for thesuperantigen after specific AAbs binding interference. Thefurther study on how change of this profile of T-cellexpansion/deletion can prevent the retrovirus-inducedimmunosuppression and cytokine dysregulation is required.

Patients infected with HIV display a progressive loss ofCD4 + Th cell function, often taking years before cell numbersand other cell functions are depressed sufficiently to produceAIDS.30 The loss of resistance to HIV infection and/orprogression to AIDS may be dependent on a switch from Thl-to Th2-subset dominated responses.5 Progression to AIDS ischaracterized by decrease in Thl-cytokine (IL-2 and IFN-y)production concomitant with an increase in Th2-cytokine(IL-6 and IL-10) production. Thl and Th2 cytokine profiles inretrovirus-infected mice are in accordance with this hypoth-esis.9'10 Injection of TCR V/I CDR1 peptide in murine AIDSsignificantly prevented the retrovirus-induced suppression ofIL-2 and IFN-y secretion. IL-2 is an important growth factorfor T cells, and its increased release after TCR V/I CDR1peptide injection is in accord with restored T-cell proliferationin retrovirus-infected mice. IFN-y has multiple distinctbiological activities including anti-viral activity, activationof macrophages and phagocytosis, and stimulation ofcytotoxicity by NK cells and cytotoxic T lymphocytes.3'Thus, increased IFN-y by TCR V/ CDR1 peptide would beexpected to restore suppressed cell-mediated immunity inmurine AIDS. Increased production of IFN-y by TCR V/CDR1 peptide in retrovirus-infected mice is also in agreementwith the enhancement of NK cell activity by the peptide. Onthe other hand, IFN-y inhibits Th2 cytokine secretion, whichusually is elevated during development of murine AIDS. Thisnotion is supported by our findings that immunization withTCR V/I CDR1 peptide in murine AIDS significantly reducedretrovirus-induced elevation of IL-6 and IL-10 production.Taken together, the prevention of imbalanced Thl and Th2cytokine production by TCR V/ CDR1 peptide injectioncontributes to the normalization of entire immune response,thereby retarding the development of murine AIDS.

In vivo, activated B cells and macrophages from HIVpatients produce high levels of IL-6 and TNF-a,32 as do LPS-stimulated splenocytes and peritoneal macrophages for MuLVretrovirus-infected mice.9 Increased IL-6 production couldexplain the hyper-y-globulinemia and global B-cell dysfunctionseen with both pathogens.33 IFN, vitamin E and theircombined administration significantly normalized the increasedproduction of IL-6 by LPS-stimulated splenocytes from retro-virus-infected mice. As IL-6 and other Th2 cytokines arerequired to maintain hyper-y-globulinemia and global B-celldysfunction of murine AIDS, their reduced production, oraltered restoration of IFN or vitamin E, would preventexcessive B-cell activity, including eventual B-cell lymphoma.IL-6 also governs the production of acute-phase reactantsby hepatocytes and their tissue damage.34 Elevated levels ofIL-6 have been associated with the stimulation of HIVreplication in macrophages and T cells.35'36 Thus normalizationof elevated levels of IL-6 by IFN and vitamin E should

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Effects of TCR peptide immunization 203

ameliorate pathological symptoms initiated by the murineretrovirus, explaining the partial normalization of spleenweight.

In summary, these studies provide the basis for futureinvestigations on the use of TCR peptide injection for thetreatment of murine AIDS and other retrovirus infection. Wenow have data suggesting that TCR peptide injection is safeand well tolerated in mice. Importantly, administration ofTCRV/I CDR1 peptide is a potentially immunomodulating agentthat achieves its immune-enhancing effects through indirectmechanisms, possible through preventing selective expansionof TCR V/I T cells induced by the chronic retroviral antigenexposure. These findings help understand the mechanismscontributing to retrovirus-caused immunodeficiency and sub-stantial malnutrition. TCR peptide injection could preventimmune dysfunction because of retrovirus infection or otherimmune deficiencies.

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2. CLERICI M. & SHEARER G.M. (1993) A THI -1 TH2 switch is acritical step in the etiology of HIV infection. Immunol Today 14,107.

3. BRADLEY W.G., OGATA N., GOOD R.A. & DAY N.K. (1993)Alteration of in vivo cytokine gene expression in mice infectedwith a molecular clone the defective MAIDS virus. J AIDS7, 1.

4. SHER A., GAZZINELLI R.T., OSWALD I.P. et al. (1992) Role ofT-cell derived cytokines in the downregulation of immuneresponses in parasitic and retroviral infection. Immunol Rev127, 183.

5. WANG Y., HUANG D.S., GIGGER P.T. & WATSON R.R. (1993) Thekinetics of imbalanced cytokine production by T cells andmacrophages during the murine AIDS. Adv Biosci 86, 335.

6. GAZZINELLI R.T., MAKINO M., CHATTOPADHYAY S.K. et al. (1992)Preferential activation of Th2 cells during progression of retro-virus-induced immunodeficiency in mice. J Immunol 148, 182.

7. KANAGAWA 0., VAUPEL B.A., GAYAMA S., KOEHLER G. & KOPF M.(1993) Resistance of mice deficient in IL-4 to retrovirus-inducedimmunodeficiency syndrome (MAIDS). Science 262, 240.

8. DEHGHANPISHEH K., HUANG D.S. Schuter S.F. Watson R.R. &MARCHALONIS J.J. (1995) Production of IgG autoantibodies to T-cell receptors in mice infected with the retrovirus LP-BM5. IntImmunol 7, 31.

9. VICTOR-KOBRIN C., BONILLA F.A., BARAK A. & BONA C. (1989)Structural correlates of a regulatory idiotype. Immunol Rev 110,151.

10. MARCHALONIS J.J., KAYMAZ H., DEDEOGLU F., SCHLUTER S.F.,YocuM D.E. & EDMUNDSON A.B. (1992) Human autoantibodiesreactive with synthetic autoantigens from T-cell receptor f chain.Proc Natl Acad Sci USA 89, 3325.

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12. FAUCI A.S. (1993) Multifactorial nature of human immuno-deficiency virus disease: implications for therapy. Science 262,1011.

13. SELVEY L.A., MORSE H.C., GRANGER L.G. & HODES R.J. (1993)Preferential expansion and activation of Vfl5+CD4+ T cells inmurine acquired immunodeficiency syndrome. J Immunol 151,1712.

14. SOUDEYNS H., REBAI N., PANTALEO G.P. et al. (1993) The T cell

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