Recurrent Meningococcal Meningitis with Absence of the Sixth Component of Complement: An Evaluation of Underlying Immunologic Mechanisms

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PEDIATRICS Vol. 64 No. 4 October 1 979 465

Recurrent

Meningococcal

Meningitis

with

Absence

of the

Sixth

Component

of

Complement:

An Evaluation

of Underlying

Immunologic

Mechanisms

Larry

B. Vogler,

MD, Simon

L. Newman,

PhD,

Robert

M. Stroud,

MD,

and

Richard

B. Johnston,

Jr, MD

Cellular Immunobiology Unit of the Tumor Institute, Departments of Pediatrics and

Microbiology, and Comprehensive Cancer Center, and Department of Medicine, Univer-sity of Alabama in Birmingham, Birmingham, Alabama and the Department of Pediatrics, National Jewish Hospital and Research Center, University of Colorado School of

Medi-cine, Denver, Colorado

ABSTRACT. A 5#{189}-year-old black girlwith recurrent

men-ingococcal meningitis and absence of the sixth component ofcomplement (C6) is reported. To explore the

pathogen-esis of recurrent neisserial infections in C6 deficiency, a

detailed analysis of her immune competence was

con-ducted. Her serum had normal chemotactic, opsonic,

alternative complement pathway, and specific antibody activity, but lacked complement-mediated bacteriolytic activity. In addition, her C6-deficient serum was

indistin-guishable from normal serum in a complement-dependent assay of phagocyte bactericidal activity. Absent

bacteri-olysis remains the only consistent defect associated with recurrent neisserial infections and absence of one of the late-acting complement components. Pediatrics

64:465-467, 1979; Neisseria meningitidis, immunologic defi. ciency, complement, meningitis.

Repeated bacterial infections occurring in indi-viduals with congenital deficiencies of C3, C5, C6, C7, or C8 ifiustrate the importance of the comple-ment system in host 2 In regard to their

role in antibacterial defense, the terminal compo-nents C6 to C9 are known to be required only for

bacteriolysis in vitro and endotoxin inactivation in

vitro or in vivo.’ Since patients who lack normal

phagocyte function are not adequately protected

Received for publication Oct 18, 1978-i accepted Jan 8, 1979. Reprint requests to (L.B.V.) 224 Tumor Institute, University of Alabama in Birmingham, University Station, Birmingham, AL

35294.

American Academy of Pediatrics.

from bacterial infection by bacteriobysis, this proc-ess has not been considered important in host de-fense. However, back of C6, C7, or C8 has been associated with a unique predisposition to neisserial infections in previous reports.9

The results of studies to define the cause of recurrent neisserial infections in the third person reported with absence of C6’#{176}are described here.

CASE REPORT

This black girl had been healthy until 5#{189}years of age when she developed meningitis, septicemia, and associ-ated purpura due to Neisseria meningitidis, group Y. In vitro testing showed the organism to be sensitive to penicillin, and the patient was treated with parenteral penicillin in high doses for 10 days. She recovered fully and was well until 10 months after discharge when she again developed meningitis and septicemia due to N meningitidis, group Y. Complete recovery was again

ef-fected by parenteral penicillin therapy.

During the second hospitalization her white blood count was 25,500 cu mm with 51% juvenile and 28% mature neutrophils. Erythrocyte examination for Howell-Jolly bodies (evidence of functional asplenia) and tests for sickle cell disease were negative. Serum

immunoglob-tiliris M, G, A, D, and E were within normal ranges.

Specific antibody titers against typhoid H and 0 antigens,

human A and B erythrocytes and sheep erythrocytes

were also normal. Convalescent serum had elevated an-tibody titers to N meningitidis, group Y organisms by

indirect immunofluorescence (1gM 1 :512, IgG 1 :2048, IgA

1 : 512) and bactericidal assay (1 :256) and to N meningi-tidis outer membrane proteins by enzyme-linked immu-nosorbent assay. Surprisingly no antibody to N

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E -.5.. (I) 0 C 0 0 C.) 0 C., 0 In a) Sc, 0 > 06 60 120 Time (mm)

* Hemolytic units are calculated on serum titration

recip-rocals; a difference of two dilutions is considered signifi-cant.

466 RECURRENT MENINGOCOCCAL MENINGITIS

in convalescent sera by hemagglutination, and absorption of sera with group Y polysaccharide antigens did not affect the bacterial antibody titer (data not shown). When subsequently immunized with a polyvalent group Y pol-ysaccharide vaccine, however, a normal antibody re-sponse was demonstrated. T (sheep erythrocyte-roset-ting) and B (surface immunoglobulin-bearing)

lympho-cytes were present in normal numbers. An extensive coagulation profile including prothrombin time, partial thromboplastin time, whole blood clotting time,

pro-thrombin consumption, fibrinolysis, clot retraction, plate-let aggregation, and assays for factors XII, Fletcher, Fitz-gerald, XI, IX, VIII, VII, X, V, II, I, and XIII revealed no abnormalities.

The patient lived with a maternal great aunt. Her mother was severely retarded and the identity of her father was unknown. No other relatives could be located and none were known to have recurrent infections, au-toimmune disease, or bleeding disorders.

MATERIALS

AND METHODS

Fresh serum samples were stored at -70 C and were thawed only once prior to examination. He-molytic complement (CH5O) was determined by the method of Kent and Fife.” Individual complement components were evaluated functionally by the method of Nelson et al’2 and immunochemically by radial immunodiffusion.’3 Functional C6 was also assayed with C6-deflcient rabbit serum.3 Phagocytic bactericidal activity for Escherichia coli and

Staphylococcus aureus and the ability of the

pa-tient’s serum to promote phagocytic killing of N

meningitidis, group Y were studied by using a

modification of a previously published method.’4

RESULTS

The patient’s serum was found to back comple-ment-dependent hemobytic activity during the sec-ond hospitalization. On analysis of individual

com-TABLE. Analysis of Complement Activity in Serum from a Patient with C6 Deficiency

Hemolytic Activity Protein Concentration

(units/ml) (mg/mI)

Patient Normal Patient % of Normal

Reference Reference

Cl 16,000 24,000 C4 46,000 46,000

C2 3,200 6,400

C3 3,200 3,200

CS 4,800 4,800 71 93

C6 <10 64,000 Undetectable 0

C7 64 64 109 198

C8 8 24 45 82

C9 8,000 8,000

Figure. Enhancement of phagocytosis of N meningiti-dir, group Y by normal and C6-deficient (C6-D) sera; 4%

and 2% refer to the final concentration of serum in the

reaction mixture. Sera were fresh except as noted. In the absence of phagocytes there was no significant difference in survival of bacteria in mixtures with 4% or 2% fresh or complement-inactivated (heated) serum. There was no killing by phagocytes in the absence of serum. One of two experiments giving identical results is shown.

plement components, C6 was undetectable by both hemolytic and immunochemical assay (Table). Ad-dition of the patient’s serum to normal serum and assay for C6 activity gave a result expected by dilution only, excluding the presence of an inhibitor as the cause of C6 deficiency. The ability of this patient’s C6-deficient serum to opsonize zymosan for phagocytosis,’5 to generate chemotactic factors on exposure to zymosan,’6 and to activate the alter-native complement pathway’7 were normal. Her C6-deficient serum, however, failed to kill N

meningi-tidis, group Y organisms by complement-mediated

bacteriolysis at a concentration that resulted in

>90% lysis with control sera.’8 When tested against

E

coli and S aureus in the presence of normal

serum, the patient’s phagocytes demonstrated nor-mal bactericidal activity.

To more specifically explore the pathogenesis of neisserial infections in C6 deficiency, the function of this patient’s serum was studied in an assay of phagocyte bactericidal activity against N

meningi-tidis, group Y. If the bate-acting components play a

role in the kffling of ingested bacteria, phagocytic bactericidal activity in the presence of the patient’s serum would be defective. As shown in the Figure, phagocytic bactericidal activity was equivalent in C6-deficient and normal sera at two different serum concentrations.

Family studies showed that the mother and uncle of the patient were heterozygous for C6 deficiency, having 42% and 39% of the normal levels of this

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ARTICLES 467

component respectively. Serum C3, C4, and CH5O values were normal in all family members. HLA-A, B and D determinants were established in available family members by serobogic-microcyto-toxicity assay’9 and mixed lymphocyte responses.#{176} The propositus was Aw24,B27/Aw34,B5; no linkage could be established between HLA determinants and C6 deficiency.

DISCUSSION

As in other people with late-acting complement component defects, our patient’s serum lacked bac-teriobytic activity, but provided normal chemotac-tic, opsonic, alternative complement pathway and specific antibody activity. The lack of antibodies to group Y polysaccharide antigens following natural infection and subsequent normal response to these antigens after immunization with a polyvalent group Y polysaccharide vaccine is noteworthy, but of unknown clinical relevance. In addition, her C6-deficient serum promoted normal phagocytic killing of N meningitidis, group Y organisms.

Study of available family members demonstrated the autosomal codominant mode of inheritance of the gene responsible for C6 production. There was no correlation of the defect with recognized prod-ucts of the major histocompatibiity complex. Blood and histocompatibility typing studies did not ac-count for the unexpected heterozygosity of the pa-tient’s unrelated uncle. Unfortunately there were no other relatives of this patient available for study.

Our analysis of this patient’s defect and results obtained from the study of other people lacking terminal complement components support the im-portance of bacteriobysis in host defense. They fail, however, to provide a suitable explanation for the unique position of Neisseria in exploiting this im-munobogic defect. Recent reports of C6 deficiency7 reflect both its prevalence and a greater awareness by physicians of the clinical manifestations of this disorder. The consistent association of C6 defi-ciency with recurrent, serious neisserial infections warrants a screening for this defect in patients with nonepidemic meningococcal meningitis or with re-peated neisserial infections. Measurement of com-pbement hemolytic activity (CH5O) provides a read-ily available assay for this purpose.

ACKNOWLEDGMENTS

This work was supported in part by grants from the Veterans Administration and the National Institutes of Health grants AI07051, AI14148, CA16673, CA13148, 1F32CA05776, and 5M01-RR32.

We gratefully acknowledge Drs J. S. Sundsmo and J.

G.

Curd for performing immunochemical determinations of C6; Dr R. Snyderman for performing chemotaxis as-says; Dr C. Frasch for determination of antimeningococ-cal antibodies; Dr R. B. Polhill for help in alternative pathway determinations; Dr M-C. Peon for coagulation analyses; and the technical expertise of Ms D. Chadwick,

Ms L Guthrie, and Ms M. Cunningham.

REFERENCES

1. Johnston RB Jr, Stroud RM: Complement and host defense against infection. J Pediatr 90:169, 1977

2. Agnello V: Complement deficiency states. Medicine 57:1, 1978

3. Leddy JP, Frank MM, Gaither T, et al: Hereditary deficiency of the sixth component of complement in man. I. Immuno-chemical, biologic, and family studies. J Clin Invest 53:544, 1974

4. Lim D, Gerwurz A, Lint TF, et al: Absence of the sixth

component of complement in a patient with repeated epi-sodes of meningococcal meningitis. J Pediatr 89:42, 1976 5. Glass D, Raum D, Balavitch D, et al: Inherited deficiency of

the sixth component of complement: A silent or null gene. J

Immunol 120:538, 1978

6. Clough JD, Clough ML, Mansfield L, et al: Complement and

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8. Lee TJ, Utsinger PD, Yount WJ, et al: Deficiency of the seventh component ofcomplement associated with recurrent Neisseria infections. Clin Res 25:379A, 1977

9. Peterson BH, Graham JA, Brooks GF: Human deficiency of the eighth component of complement. The requirement of Cs for serum Neisseria gonorrhoeae bactericidal activity. J Clin Invest 57:283, 1976

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1979;64;465

Pediatrics

Larry B. Vogler, Simon L. Newman, Robert M. Stroud and Richard B. Johnston, Jr

Complement: An Evaluation of Underlying Immunologic Mechanisms