Serum immunoglobulin profile in normal Kashmiri adults.GA Bhat, M Mubarik, MY Bhat
Department of Medicine, S.M.H.S. Hospital, Srinagar, Kashmir.
Serum levels of the immunoglobulins IgG, IgA and IgM were estimated in 102 apparently healthy Kashmiri adults in the age group of 16-60 years, using single radial immunodiffusion method of Mancini et al. The mean serum levels of IgG, IgA and IgM were observed to be 1289.19 +/- 234.9, 216.18 +/- 50.70 and 118.97 +/- 41.88 respectively. No significant difference in the mean serum levels was observed between the two sexes as such, but IgM showed a significant increase in females in the age group of 16-30 years. IgA showed a significant increase with age, with no such increase in case of IgG and IgM.
Keywords: Adolescent, Adult, Age Distribution, Comparative Study, Enzyme-Linked Immunosorbent Assay, Female, Human, Immunoglobulin A, blood,Immunoglobulin G, blood,Immunoglobulin M, blood,India, Male, Middle Age, Population Surveillance, Reference Values, Sex Distribution,
Immunoglobulins are glycoproteins comprising 82-96% polypeptide and 4-18% carbohydrate. Human Immunoglobulins have been assigned to five classes i.e. IgA, IgD, IgE, IgG, IgM. Three major Immunoglobulins of serum i.e. IgG, IgA and IgM are the most frequently investigated. The various serological methods, used for immunoglobulin estimation include single radial immuno-diffusion (SRID), Radio-immuno assay (RIA), Enzyme linked immunosorbent assay (ELISA) etc. The levels show variation depending upon age, sex, socio-economic status, environment, ethnic and hereditary state of an individual. Further, variation is also observed in various disease states,. For the proper interpretation of immunoglobulin variation in various diseases, it is mandatory to have a baseline data of the normal levels among the different population groups.
The present study was, therefore, conducted to establish normal values of the serum Immunoglobulins IgG, IgA and IgM in normal Kashmiri adults, the first study of this kind in the valley.
Serum IgG, IgA and IgM levels were estimated in 102 apparently healthy Kashmiri adults in the age group of 16-60 years, comprising 51 individuals from each sex. The individuals were further divided into three age groups, i.e. i) (16-29) years, ii) 30-44 years and iii) 45-60 years, each comprising 34 individuals, 17 from each sex. The individuals were taken from among the professional and paramedical hospital staff, attendants of the patients and the blood donors participating in the donation camps. The individuals belonged to one ethnic group comprising only Kashmiri Muslims. Health of each individual was evaluated in detail to rule out any clinical problem (including the parasitic infestations) or any other factor, otherwise interfering with the results.
The Immunoglobulin levels were estimated by Single-Radial Immuno-diffusion method of Mancini et al using commercially available tripartigen plates (separate for each immunoglobulin). Each plate contained a pre-prepared solidified agar-gel into which H-chain specific anti-serum (produced by immunisation of goats) to the respective Immunoglobulins (i.e. IgG, IgA and IgM) was already incorporated. Each plate had 12 wells, made out by cutting into the solidified agar. In one 5 micro-litres of control standard serum (WHO Reference serum No. 67/97, containing 770 mg IgG, 135 mgs IgA and 81 mg IgM in 100 ml) was put and rest of the wells were filled with 5 micro-litres of the test sera. As instructed, the plates were closed and left to stand at room temperature, till the diffusion was complete (50 hours in case of IgG and 80 hours in case of IgM). Precipitin ring diameters were measured, using a specific calibrated scale. The immunoglobulin concentration related to the measured diameters were read directly from the table of reference values. (The tripartigen plates, control serum, micro-litre pipettes, calibrated scale and table of reference values were provided by Hoechst Pharmaceuticals Ltd. Bombay).
Statistical comparisons were based on students ‘t’ test. A value of 0.05 or less was considered significant.
The mean levels of IgG, IgA and IgM were observed to be 1289.19 + 50.70 and 118.97 + 41.88 respectively. The difference in the mean serum immunoglobulin levels between the two sexes was not significant (p>0.20) [Table - 1].
The mean serum IgA levels showed an increase with age, which was significant between the age groups 30-44 years and 45-60 years (P<0.05) and between the age groups 16-29 years and 45-60 years (P<0.01). However, the difference in IgG and IgM levels between the various age groups was not significant [Table - 2].
The difference in mean serum IgM levels between the two sexes in the age group of 16-29 years was significant (p<0.01) and not significant in case of IgG and IgA (p>0.20). Further, no significant difference in the Immunoglobulin levels was observed between the two sexes in the other age groups P>0.20 [Table - 3].
The mean serum IgG, IgA and IgM levels as observed in our study, are in conformity with those of some Indian and other racial communities but differ to a varying extent when compared to some other reports [Table - 4] ,,,,,,,,.
The difference is not unexpected. The possible reasons could be i) environmental racial and genetic factors. ii) the levels are expected to vary in different laboratories and according to the technique employed. Thus, it becomes imperative that each laboratory should establish its own range of normal values. Further, normal values should also be established for each community. By this way, a proper interpretation and genuine assessment of any variation in disease states can be done,.
Effect of various factors like diet, climate, infections, occupation, social status and others on the immunoglobulin levels are limited and controversial. So far as the Kashmir valley is concerned, it is relatively a colder climatic region, having some peculiar dietary habits - (diet consisting mainly of carbohydrates). The clinical experience has revealed the region to be free of a variety of infections (like Kala-azar and malaria commonly found in tropical climates of most parts of India and abroad. The presence of the infection, as considered by Maheshwari and Singh would normally effect the immunoglobulin levels in the population. Raised serum IgG levels have been reported in cases of malaria and Kala-azar. Further except for ascariasis most of the parasitic infestations are less commonly observed in Kashmir. Kashmir has a non-migrant population, comprising only of one ethnic group. The inherited capacity of different ethnic groups to produce a certain immunoglobulin level is known. Higher levels of IgG and IgM have been reported in healthy black Africans. Further raised levels of IgG and IgM are found in Africans domiciled in U.K. when compared to those of indigenous Europeans.
We did not find any significant difference in the mean immunoglobulin levels between the two sexes in general. However the mean serum IgM levels showed a significant increase in females in the age group of 16-29 years (p<0.01), in conformity with other reports,. The increase in serum IgM in post pubertal young females can be attributed to the increased levels of female sex hormones in this group with gradual decline as menopause is reached. How ever, the exact correlation of this cause and effect needs to be confirmed and justified. Further it needs a study on a larger group of individuals in this age group between the two sexes to draw any possible conclusion. The IgA levels showed a significant increase with age. There are reports indicating that the, audit levels of serum IgG and IgM are attained by 16 years of age but IgA levels continue to rise throughout early adulthood. As it is evident the secretary surfaces remain exposed to a variety of infections ail the time. Thus, the increase in serum IgA is not surprising, as it is the most abundant naturally occurring antibody responsible for the immune surveillance of secretary surfaces.
At present it is not possible to relate a certain immunoglobulin levels (higher or lower) definitely to the factors, peculiar to various Indian and other regions abroad. However, it needs to capitalise on the possible factors with further search and research to draw some conclusions.
[Table - 1], [Table - 2], [Table - 3], [Table - 4]