Initial blood testing for predominantly antibody deficiencies

The most common immunodeficiencies are those that tend to develop in adulthood and affect antibody production. Antibodies are proteins of the immune system responsible for the recognition of germs and the activation of different immune cells. They are produced by two types of cells: B lymphocytes or B cells and plasma cells. Both are very related, in a certain way plasma cells are one of the evolutionary paths of B lymphocytes. When the immune system fails in antibody production, a situation that we call hypogammaglobulinemia occurs, building this word from the prefix «hypo» (low), gammaglobulins (antibodies) and the suffix «emia» (in blood), that is, low antibodies in blood. Hypogammaglobulinemia can respond to several causes and affect different types of immunoglobulins, although when we use this term, it is usually because it affects almost all types of antibodies. Antibody production deficits can be accompanied by a single decrease in IgA, IgM, or IgG antibodies, or can affect several of them. When the deficiencies are symptomatic, they usually affect more than one type of antibody, usually IgG and some of the other types of antibodies. Although hypogammaglobulinemia can predispose to various infections, a common pattern is that of lower respiratory tract infections (bronchitis and pneumonia) and repeated gastrointestinal (diarrhea) infections. To know the degree of immunocompetence of antibody immunity, it is necessary to perform several tests that interrogate the amount of antibodies and the function and distribution of the cells that produce them.

To properly evaluate hypogammaglobulinemia, especially those that affect more than one type of antibody (IgG + IgA, IgG + IgM or IgG + IgA + IgM), it is necessary to know the quantification of the different isotypes of antibodies IgG, IgA, IgM, IgE in blood, know the subclasses of IgG (IgG-1, IgG-2, IgG-3, IgG-4) and perform a proteinogram and immunofixation to rule out that the cause of hypogammaglobulinemia is due to the presence of a hematological disease.

To evaluate the function of antibodies, I will probably ask you to get vaccinated with several types of vaccines. This will allow us to know in more detail whether the antibody-producing cells are intact or have a certain degree of malfunction. The most common vaccines are those for pneumococcal polysaccharide antigens and Salmonella Typhi, and tetanus toxoid vaccines. As we want to evaluate if there is antibody production after vaccines, two analytical extractions are necessary, one first before the vaccines, and another post-vaccination to be carried out between 3 and 4 weeks after the administration of the vaccines.

On the other hand, it is interesting to know what is the distribution of the different groups (subpopulations) of lymphocytes, including those that produce antibodies. This B-cell memory study gives us information about the number of new B cells, how many have already been trained against the germ they recognize, and how many are producing antibodies. Below is a list of codes for the performance of these tests:

REFERENCE 44789 VARIABLE COMMON IMMUNODEFICIENCY AND RELATED DISORDERS, MASSIVE SEQUENCING PANEL (NGS) 52 GENES

REFERENCE 75106 TETANUS ANTIBODIES IgG SERUM

REFERENCE 55650 STREPTOCOCCUS PNEUMONIAE ANTIBODIES IgG SERUM

REFERENCE 66595 SALMONELLA TYPHI Vi ANTIBODIES IgG SERUM

REFERENCE 75128 LYMPHOCYTE IMMUNOPHENOTYPING (IMMUNE SYSTEM) WHOLE BLOOD (SPECIFY B-CELL MEMORY STUDY).