Factors Influencing Antibody Production

When a foreign antigen entered in body, immune system respond against it by producing antibody. There are certain factors those determined the immune response against any antigen. This immune response may vary from person to person. Thus, certain factors are considered to determine the seriousness of such immune responses.

Genetic Factors

The immune response is under genetic control. The difference in immune response to the same antigen shown by different individuals in a species is determined by genetic differences. 

The term ‘responder’ and ‘nonresponder’ are used to describe the individual’s capacity to respond to a particular antigen. The Ir (immune response) gene control this property.

Age

The embryo is immunologically immature.

The capacity to produce antibodies starts only with the development and differentiation of lymphoid organs.

The age at which embryos acquire immunological competence varies with different species.

During embryonic life, when the potential immunocompetent cell comes into contact with its specific antigen, the response is elimination of the cell or induction of tolerance. This is believed to be the basis for the non antigenicity of self antigens.

During embryonic life, the developing lymphoid cells come into contact with all the tissue antigens of the body released by cellular breakdown, so that all the clones of cells that have specificity towards self antigens are eliminated.

Immunocompetence is not complete at birth, but continues to develop as the infant grows.

From 3 – 6 months of age, the infant has to depend on itself for antibody production, by which time the maternal antibodies disappear.

However, full competence is acquired only by about 5 – 7 years of IgG and 10 – 15 years of IgA. The ontogeny of antibody response also depends on the antigens concerned.

Nutritional Status

Immune response is adversely effected by malnutrition, though serum components necessary for immunity are conserved selectively till the nutritional deficiency becomes marked.

Protein calorie malnutrition suppresses both humoral and cellular immune responses, the latter more severely.

Deficiencies of amino acids (tryptophan, phenyl alanine, methionine, glycine, isoleucine) and vitamins (Vitamin A, and B group factors riboflavin’s, pyridoxine, pantothenic acid, folic acid) have been shown to cause a decrease in antibody synthesis.

Route Of Administration

The humoral immune response is better following parenterally administration of antigen than through oral or nasal routes. large particulate antigens, such as bacteria or lymphocytes, are more effective when injected into tissues.

The route of administration may also influence the type of antibody produced. For production of IgA antibodies, the oral or nasal route is most suitable.

Inhalation of pollen antigens induces IgE synthesis, whereas the same antigens given parenterally lead to IgG antibodies. 

With some antigen the route of administration determines whether tolerance or antibody response results.

Size And Number Of Doses

Antibody response is, to an extent, dose dependent. An antigen is effective only above a minimum critical dose. Further increase in dose enhances the intensity of the antibody response. But beyond a certain level, increase in the dose of antigen does not improve the antibody response but may even inhibit it and induce tolerance.

Multiple Antigens

When two or more antigens are administered simultaneously, the effects may vary. Antibodies may be produces against the different antigens just as though they had been given separately or antibody response to one or the other of the antigens may be enhanced, or the response to one or more of them may be diminished (antigenic competition).

When two bacterial vaccines (for example, typhoid and cholera vaccines) are given in a mixed form, the antibody response to each is not influenced by the other. When toxoids are given along with bacterial vaccines (e.g., triple vaccine containing diphtheria and tetanus toxoids along with Bord pertussis vaccine) the response to the toxoid is potentiated.  When diphtheria and tetanus toxoids are given together, with one in excess, the response to the other is inhibited. 

Gaurav Singh

Editor in Chief Medical Microbiology & RDT Labs - RDT Labs Magazine

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