to Measles Antigen. JOHN C. RUCKDESCHEL,MD; CAROLYNDUNMIRE;. MICHAELR. MARDINEY,JR., MD, Baltimore. The study of cell-associated immunity to ...
Experimental studies have duplicated the microscopic and ultrastructural abnormalities of SSPE. They also indicate many of the pathogenic mechanisms that may operate in the human disease. The rescued SSPE agents of man behave, and can be manipulated, in several ways that are identical to the behavior of standard measles strains in similar animal hosts. Persistent, subclinical infection of the animal central nervous system (CNS) with defective or cell-associated measles virus can readily be achieved after intracerebral inoculation by manipulating some of the following factors. (1) Age: age of the host at first exposure to virus is often an essential factor in experimental SSPE studies and is probably also significant in human SSPE. Completely susceptible, newborn animals usually die of overwhelming encephalitis when exposed intra cerebrally to measles or SSPE virus, while adults irradicate CNS virus rapidly. However, in immature (weanling) animals, CNS infection frequently persists following an acute, clinically apparent disease; (2) virus strain: the strain and past passage history of the experimental virus employed is extremely important. Strains that replicate normally and produce large amounts of complete, extracellular virus are less likely to establish persistent infection, while strains known to produce defectiveand. cell-associated viral products will more likely persist in the CNS; (3) host immune response: the presence of host antibody prior to or early in the infection appears to enhance persistence; perhaps by selectively segregating a defective strain from a heterogeneous viral population, or by altering viral assembly characteristics at the cell membrane; (4) immune inhibition: inhibition of host immune response acutely favors complete virus replication, increased tissue destruction, and acute disease, whereas late immunosuppression following establishment of the chronic infection may reactivate the CNS disease. The host antibody (B lymphocyte) response to measles infection is often enhanced in persistent infection as it is in human SSPE. Hamsters inoculated with SSPE strains raise serum antibodies to all the known antigens of measles virus. Little is known of the cellular (T lymphocyte) immune .activity; however, relatively selective inhibitors of T cell function (antilymphocyte serum Or neonatal thymectomy) stimulate virus replication and the appearance of active disease. Animal studies suggest that humanSSPE may result when infants, at a critical age, are infected with measles' the virus persists in the CNS in a defective state with the production of structural components and intracellular' antigens but without assembly of complete virus at the cytoplasmic membrane. The defective viral state may dev~lop beca?se of immaturity of the CNS, as the result of VIral modification and suppression by the antibody reor both. Little has been learned from animal of the factors that reactivate viral replication to mittats clinical SSPEor of measures that may adequately suppress viral activity. Jreatment of SSPE: Review of Current Treatments tJfiJDDVUn., MD,Memphis; DANILO A. DUENAS MD lVl1emphis; Atlanta' , awarenessofSSPEfollowed the beginning in .1967.. Following •.• the virus and SSPE, about 20'0 cases The disease peaked at 60 decreased to the early
1960 frequency of about 20 cases per year, which. was noted prior to the increase in 1966. Therapeutic attempts in SSPE have been disappointing and frustrating for both physicians and parents .. Numerous investigators have tried to achieve a rational, scientific approach to the disease. All attempts have failed. Therapy in the 1960s included steroids in relatively high doses without any effect on the disease. Bromodeoxyuridine, an anti-DNA viral agent, was utilized with minimal improvement in some patients (Freeman). A carefully documented study, utilizing amantadine hydrochloride (Haslam) and rimantadine hydrochloride (Jabbour), has resulted in no alteration of the course of the disease. Other attempts, utilizing combinations of measles vaccine, y-globulin in large doses, and ether inhalation, were evaluated in several patients (Jabbour). The course of the disease was not altered. Recently, several attempts with transfer factor, given parenterally and by intrathecal route, have been utilized (Sever and Meloff). Inosiplex (Isoprinosine) has been utilized with some alteration of the course of the disease (Mattson). Careful study of the intellectual abilities indicated that the child had some improvement, which may have been coincidental. In summary, interferon-stimulating agents, rifampin, thymectomy, andhyperimmune y-globulin, and new agents, eg, inosiplex, have been utilized with varying failures and/or successes. The investigator and patients' evaluation of success is not easily defined. The difficulty in assessing whether the child's disease remits and exacerbates is difficult unless careful deIinea~ tion of stages of the disease are established prior to the onset of treatment. The recognition of the disease in early stages, stage 1 and 2, is imperative if arrest of the disease is to provide a quality of life •consistent with self-care and achievements. Treatment following stage 1 is rarely possible,because the child is rarely recognized and referred prior to the onset of either myoclonus, convulsions, or motor abnormalities. Approximately 1'00/0 of patients will be recognized in stage 1 (Jabbour) . The clinical evaluation of the disease, utilizing staged i through 4, coupled with serial electroencephalogram~, measles antibody titers in serum and cerebrospinal flUId (CSF), and CSF (,-globulin, is helpful in predicting the COurseof the disease. In addition, improvement and arre.~t of the disease are. usually short-lived, although some chI drenmay remain in stage 2 for two to seven years. . To our knowledge, a variety of agents has be.en.usedI the treatment of SSPE and has been disappomtmg an require a reevaluation 'for a rational, predictable therapeutic regimen.
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There. have. been conflicting reports over 58 patients are immunologically defective and are able to respond to measles antigen. Using a culture system and the incorporation of as a .measureo! in vitro blastogenesis, we mononuclear cell preparations from four and from seronegative arid seropositive vc,IUlnt€iers their ability to respond to the following culture Cellular. Immunity. and ·~~PE_J\OSU"L'"
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(1) nonspecificmitogens phytohemaggluti~in (PHA) , concanavallin-A (con-A), and pokeweed mitogen (PWM); (2) mitomycin-treated allogeneic lymphocytes; (3) .live attenuated measles virus vaccine; (4) autoclaved vaccme; (5) live SSPE measles virus passaged in HeLa cells in tissue culture (courtesy of Dr. L. Horta-Barbosa); (6) mitomycin-treated, SSPE-infected MA-160 cells (courtesy of Joseph Bellanti and Monroe Vincent); and (7) mitomycin-treated, CMV-infected WI-'3'8 cells. Patients with SSPE showed normal responsiveness in vitro to nonspecific mitogens(PHA, con-A, and PWM) and to allogeneic cells. Efforts to stimulate lymphocytes from measles seropositive and from SSPE patients with a widerange of dilutions of either commercially available measlesvirus or virus isolated from a known case of SSPE failed to show any significant data. However, lymphocytes from SSPE patients exhibited in vitro blastogenesis in culture with SSPE virus-infected MA-160 cells but not to CMV-infected WI~38 cells. Measles seronegative and seropositivecontrols failed to show a proliferative response to the same preparations despite their ability to produce migration inhibitory factor to the SSPE virus preparation alone. It is suggested that different antigens are involved in stimulating the different responses, and that specificmeasles virus-induced cell surface antigens may be responsiblefor lymphocyte transformation, which only the SSPE-infected patients are able to recognize. Cell·AssociatedImmunity to Measles in SSPE: Evidence forImpaired Lymphocyte Transformation in Response to Measles Antigen JOHN C. RUCKDESCHEL,MD; CAROLYN DUNMIRE; MICHAEL R. MARDINEY,JR., MD, Baltimore The study of cell-associated immunity to the measles virus in patients with SSPE has long been hindered by lack of a suitable assay for in vitro lymphocyte responsiveness (IVLR) to measles. Previous assays of IVLR to measles have demonstrated generalized suppression of IVLR by measles felt to be due to the suppressive effect of the measles virus on lymphocytes. No experiments have been presented that show positive cellular immunity to measlesdespite the known importance of the cell-associated immunesystem in clinical measles (ie, the normal course of measles in agammaglobulinemic children). We have developedan assay for IVLR to measles that employs a membrane-associated viral antigen and measures tritiated thYmidineincorporation in a classical leukocyte culture system. Prior experiments in our laboratory with this assay have disclosed the following features of IVLR to measles in normal donors: (1) there is a unique doseresponsepattern for each donor, (2) the kinetics of that re~ponseare maximal on day 7' and, (3) the response is neIther diminished nor enhanced by inhibitors of viral growth. Twenty-two of 24. (91.70/0) normal donors had meanspecific increase '( SI. DPM /experimental: culturedPM/control culture).of124,390 ± 2,765. Two normal b~nors (8.30/0) with a mean SI of 6;400 ± 420 and a cord ood donor with an SI of. -'3,775± 25,550 were felt to r:p~esent equivocal or absent IVLR to measles. Two pedi~.rIC.residents with. inadequate antibody titers •(RIA I lers:o, 1:4) and normal IVLR to measles .failed to de;~ o~ measles despite frequent clinical exposure, stressing d Importance of the cellular immune system in the host e ense against measles. Three patients with SSPE, tested in parallel with
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normal donors, displayed a mean SI of 6,144 ± 1,924, significantly below that of the normal donors. Leukocytes from the SSPE patients responded comparably to normal donor leukocytes in mixed lymphocyte reactions, excluding the possibility of a generalized lymphocyte defect. It seems clear that patients with SSPE have a deficit in their cell-associated immunity that is specific for at least the measles virus. Whether this deficit extends to other antigens, viral or otherwise, is currently under study. Inhibition of Lymphocyte Stimulation by Measles Virus JOHN SULLIVAN; DAVIDBARRY; PAUL ALBRECHT; SUSAN LUCAS,Bethesda, Md The effect of measles virus on phytohemagglutinin (PHA)-induced stimulation of human peripheral blood mononuclear cells was investigated to delineate possible mechanisms for viral suppression of cell-mediated immunity (CMI). It was noted that medium that had several days' contact with uninfected monolayer's as well as unpurified measles virus preparations produced significant inhibition of tritiated thymidine incorporation by PHAstimulated lymphocytes. When partially purified measles virus preparations were used, however, marked inhibition was observed and the inhibitory effect of cell-derived factors could be separated easily from the virus-induced inhibition. Experiments to determine the mechanisms of the virusinduced inhibition of tritiated thymidine incorporation showed the following: (1) live measles virus and not ultraviolet-irradiated or head-inactivated virus-produced inhibition; (2) measles virus infected and replicated in the majority of PH A-stimulated lymphocytes; (3) the inhibitory effect observed was not due to cell death or the result of a viral-induced inhibitor being released from measles-infected lymphocytes; (4) monocytes showed minimal infection by measles virus and monocyte depletion had no effect on the ability of measles virus to inhibit tritiated-thymidine incorporation by PHA-stimulated lymphocytes. Since it was found that measles virus-infected lymphocytes display an impaired response to in vitro PHA stimulation, perhaps this dysfunction may be extended to mediator release and other functions associated with delayed cutaneous hypersensitivity in vivo. Lymphocyte Blastogenesis to Viral Antigens in SSPE EARL B. MATTHEW,San Antonio, Tex; MARYKRASNY; DAVIDA. FUCCILLO;JOHN L. SEVER,Bethesda, Md It has been suggested that the chronic measles infection of SSPE is related to a defect in cell-mediated immunity to measles virus. Lymphocyte blastogenesis, as measured by tritiated thymidine uptake, was used as the assay of specific viral antigen recognition to measles, mumps, and varicella in seven patients with SSPE (nine tests), and ten normals. Phytohemagglutinin was also tested. Measles virus was grown in human heart tissue, mumps in embryonated egg, and varicella, in.WI-38 tissue. Control antigens were prepared with the same tissues. Fetal calf serum was used as the protein source. No significant stimulation (>3 X ratio 'of antigen to control Ag cpm) to measles occurred in six individuals with SSPE. In. the seventh, no response was ,.found to measles on the initiaLtest, but did respond after leukophoresis. ' Only 'two
Cellular
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