Serum immunoglobulin concentrations in epidemic meningococcal meningitis in Niger.

SERUM IgM LEVELS IN EPIDEMIC MENINGOCOCCAL MENINGITIS 837 Serum Immunoglobulin Concentrations in Epidemic Meningococcal Meningitis in Niger by D. S. ROWE,' M. VANDEKERKOVE 2 & B. GRAB 3 By comparison with the frequency of nasopharyn- geal carriers, meningococcaemia and meningococcal meningitis are rare events. In a study of army recruits in the USA, Goldschneider, Gotschlich & Artenstein (1969) showed that the absence of pre-existing immunity, as indicated by a lack of bactericidal antibodies, was an important factor in the establish- ment of blood and meningeal infections. There was however no evidence of an immunodeficiency in susceptible individuals, since the specific antibodies occurred early in infection and total serum immuno- globulin levels were normal (Artenstein, 1967). It was concluded that lack of immunity in the recruits was related to insignificant previous exposure to meningococcal antigens. Two studies on different populations in the United Kingdom have, however, suggested that a form of immunodeficiency may be important in these diseases under certain circumstances. Hobbs, Milner & Watt (1967) studied 5 children with meningococcaemia or meningitis aged from 8 months to 8 years; 3 children were considered to show unusually low concentra- tions of total serum IgM on at least one occasion, and 2 of these children died of fulminating infections. The authors concluded that IgM antibodies consti- tute an important defence mechanism against menin- gococcal infection and the possibility was raised that fulminating meningococcaemia is associated with IgM deficiency. In a study of 131 hypogammaglobu- linaemic individuals, Soothill & Rowe (1971) re- ported that the 12 cases of meningitis in the group (of unspecified cause) occurred only in those individ- uals having quantitative or qualitative deficiencies of IgM, as indicated either by low serum levels or by low levels or absence of isohaemagglutinins. Meningococcal meningitis occurs commonly in 1 Head. WHO Immunology Research and Training Centre, and Director, WHO International Reference Centre for Immunoglobulins, University of Lausanne, Switzerland. 2 Chef de Laboratoire, Laboratoire de Recherches de Microbiologie, Centre d'Instruction et de Recherches du Service de Sante des Troupes de Marine, Marseille, France. 3 Statistician, Health Statistical Methodology, WHO, Geneva, Switzerland. epidemic form in central Africa, where there is a high mortality. Attempts at control by active immu- nization might be vitiated if susceptibility in this population were related to an immunoglobulin defi- ciency. Although serum IgG, IgM, and IgE concen- trations are frequently elevated in native Africans, wide ranges are observed (Rowe et al., 1968), so that the possibility of deficiency cannot a priori be ex- cluded. We have accordingly studied the concentra- tions of immunoglobulins in the sera of 45 African patients presenting during an epidemic of meningo- coccal meningitis, and of 82 African controls. Methods Selection of subjects. All serum samples were ob- tained from residents of the Republic of Niger; 45 samples were obtained from patients with menin- gococcal meningitis living in the town of Niamey. The diagnosis was established by clinical examination and the finding of turbid or purulent cerebrospinal fluid. Cell samples showed Gram-negative intracellu- lar diplococci. In 25 cases, meningococci of sero- type A were demonstrated after culture. The remain- ing 82 control samples were from 380 sera obtained in the towns of Niamey and Dosso, and the villages of Lamordi Torodi and Damana, selected to match, as far as possible, the age distribution of the patient group. All individuals in the control group were contacts of patients having meningococcal meningi- tis. On the basis of a single bacteriological examina- tion, 8 of the control group were found to be carriers. Serum studies. Serum samples were obtained by venepuncture during the first few days of the disease, and were stored and transported in liquid nitrogen containers. Immunoglobulin concentrations were measured at the WHO International Reference Centre for Immu- noglobulins by single radial diffusion in gel contain- ing specific anti-immunoglobulin antisera, using a technique similar to that of Mancini, Carbonara & Heremans (1965). The IgE precipitates were rendered 2775B NOTES visible by an autoradiographic procedure (Rowe, 1969). Measurements of IgG, IgA, and IgM were made by direct comparison with working standards consisting of serum having elevated contents of these immunoglobulins. The working standards were com- pared with a preparation related to the WHO Inter- national Reference Preparation for IgG, IgA, and IgM (Rowe, Anderson & Grab, 1970; WHO Expert Committee on Biological Standardization, 1971), and a statistical analysis of dose-response curves showed them to contain 260 IU of IgG per ml (95 % confi- dence interval 225-301), 270 IU of IgA per ml (95 % confidence interval 254-287), and 682 IU of IgM per ml (95% confidence interval 638-729). The reference preparation for IgE (68/341) contained 10 000 units per ampoule. Results Since concentrations of serum immunoglobulins varied significantly with age, patients and controls were divided into four age groups, as shown in Table 1. Table 2 shows the serum immunoglobulin levels in these groups. The mean concentrations of the control sera were slightly lower than those of the patient group for IgG, IgA, and IgM, but were slightly higher for IgE. In no case was the difference significant at the 5% probability level. Similar distri- butions of immunoglobulin levels were found in both patient and control groups, the range of levels for IgM and IgE being much wider than for IgA and IgG. The inclusion of individuals from different areas in the control group was justified only if there were no differences of immunoglobulin content between areas. Further analyses showed no significant differ- Table 1. The four age groups of patients and controls Age Patients Controlsa groups r(years) No. [_% No. |_% 3-9 13 28.9 19 23.2 10-19 17 37.8 29 35.4 20-39 13 28.9 26 31.7 > 40 2 4.4 8 9.8 total f 45 100 - 82 100 a Includes 1 individual in the 3-9 years age group and 7 indivi- duals in the 10-19 years age group who were shown to be carriers. Table 2. Serum immunoglobulin levels in the four age groups of patients and controls Patients Controls Age Mean Mean (years) concen- Standard concen- Standardtration deviation tration deviation (IU/ml) (IU/ml) IgG 3-9 184.8 56.8 191.3 47.1 10-19 213.0 46.9 195.7 54.9 20-39 194.6 53.0 200.2 41.3 3 40 156.0 51.5 160.9 53.8 total 197.0 52.2 192.7 49.3 IgA 3-9 159.5 63.2 145.5 44.5 10-19 175.0 61.8 140.6 39.3 20-39 144.1 43.4 156.1 52.2 > 40 135.0 19.1 158.6 39.9 total 159.8 56.5 148.4 [ 44.8 IgM 3-9 308.5 150.2 277.8 168.7 10-19 494.7 189.8 392.0 139.6 20-39 415.5 183.1 375.6 169.3 >40 272.8 106.1 291.6 195.5 total 408.1 188.0 350.6 166.2 IgE 3-9 1 738.4 1 744.7 3 680.8 3 680.9 10-19 3 211.2 3 696.8 3 848.3 3 536.8 20-39 4 728.7 3 861.4 3 906.0 2 942.5 >40 976.5 587.8 2 650.5 3 558.2 total 3 124.8 3 378.7 3 710.9 3 351.7 ences in immunoglobulin levels between areas. More- over, the mean levels of immunoglobulins in the 24 control sera from Niamey itself did not differ significantly from the mean levels in the patient group. 838 SERUM IgM LEVELS IN EPIDEMIC MENINGOCOCCAL MENINGITIS 839 Discussion Susceptibility to meningococcal meningitis has been shown to be related to the absence of pre- existing serum antibodies (Goldschneider, Gotschlich & Artenstein, 1969). Although susceptible army re- cruits in the USA showed no evidence of immuno- globulin deficiency, there is some evidence from studies of young children and of persons with hypo- gammaglobulinaemia that immunodeficiency, espe- cially of IgM, may be a predisposing factor. The results obtained in this study show no immunoglo- bulin deficiency associated with epidemic meningo- coccal meningitis in Africans. The findings therefore resemble those obtained in the American study, and extend them to a different population and to another immunoglobulin-namely, IgE-which may play some role in protective immunity in the respiratory tract. Recent studies have indicated that factors such as climate, dryness of the air, and seasonal over- crowding may favour the spread of infection in Africans (Ghipponi et al., 1971). Since there is no evidence of immunodeficiency associated with menin- gitis in Africans, at least in terms of a lack of serum immunoglobulins, there is no reason to suppose that control of the disease by an effective vaccine may not be possible. ACKNOWLEDGEMENTS The authors acknowledge the skilled technical assis- tance of Miss Marianne Stella and Mr Michael McGinnis, WHO International Reference Centre for Immuno- globulins, Lausanne. REFERENCES Artenstein, M. S. (1967) Lancet, 2, 841 Ghipponi, P., Darrigol, J., Skalova, R. and Cvjetanovic, B. (1971) Med. trop., 31, 197 Goldschneider. I., Gotschlich, E. C. & Artenstein, M. S. (1969) J. exp. Med., 129, 1307 Hobbs, J. R., Milner, R. D. G. & Watt, P. S. (1967) Brit. med. J., 4, 583 Mancini, G., Carbonara, A. 0. & Heremans, J. F. (1965) Immunochemistry, 2, 235 Rowe, D. S. (1969) Bull. Wld Hlth Org., 40, 613 Rowe, D. S., Anderson, S. G. & Grab, B. (1970) Bull. Wld Hlth Org., 42, 535 Rowe, D. S., McGregor, I. A., Smith, S. J., Hall, P. & Williams, K. (1968) Clin. exp. Immunol., 3, 63 Soothill, J. F. & Rowe, D. S. (1971) In: Hypogamma- globulinaemia in the United Kingdom, London, Her Majesty's Stationery Office (Medical Research Council Special Report Series No. 310), p. 55 WHO Expert Committee on Biological Standardization (1971) Wld Hlth Org. techn. Rep. Ser., No. 463 A Capillary Tube Agglutination Test for Malaria by H. F. KORTMANN,1 J. LELIJVELD,2 J. P. J. RoSS 3 & K. F. LOHR 4 A number of serological techniques have been used for assessing circulating antibodies in subjects with current or previous malarial infections, and their application to the study of malaria has been reviewed by Voller & Bruce-Chwatt (1968). Most of the older tests such as precipitation, agglutination, and complement fixation have not proved completely 1 Research Officer, East Africa Institute of Malaria and Vector-Borne Diseases, Amani, Tanzania. I Director, East African Institute of Malaria and Vector- Borne Diseases. 3 Senior Veterinary Research Officer in charge of Proto- zoology Section, Veterinary Research Laboratory, Kabete, Kenya. ' Veterinary Research Officer in charge of Parasitology Section, Veterinary Research Laboratory, Kabete, Kenya. satisfactory, and of the newer techniques the indirect haemagglutination test has yet to be thoroughly established; immunofluorescence tests alone have been developed as a practicable diagnostic aid. Many of these sero-diagnostic methods are, however, of limited value because they are too complicated or require elaborate laboratory equipment and skilled technical supervision. The capillary-tube agglutination (CA) test avoids many of these difficulties and has been successfully employed to detect antibodies of several animal protozoan parasites. Ristic (1962) first described a CA test for the diagnosis of bovine anaplasmosis, using as antigen particulate suspensions of infected blood disrupted by ultrasonic oscillation. The stabi- 2775c