Traditionally, immunodeficiency illnesses have been described as problems in the formation and function of T and B cells, the key effector cells of specific cellular and humoral immunity, respectively. However, it has become increasingly apparent that innate immunological systems play a significant role in host defence, either acting independently or by amplifying specific T and B cell responses.
In addition, there are several illnesses that manifest identically to primary immunodeficiency disorders (PID), but are caused by acquired abnormalities such as somatic mutations.
Neutrophils and macrophages respond to local inflammatory and cellular damage signals to mediate non-specific innate immunity. These signals include pathogen surface antigens and host stress-induced chemicals.
Antigens activate stimulatory and inhibitory receptors. This relationship activates the immune system upon pathogen exposure but maintains it quiet otherwise, preventing auto-immune illness.
Antigen-specific receptors on lymphocytes bind to pathogen antigens to induce acquired immunity. Cellular immunity activates pathogen-killing lymphocytes. Plasma cells stimulated by antigenic stimulation produce antibodies in the humoral response.
Depending on the age at which they manifest, antibody deficiency can be both primary and secondary. Others depend on the activation of genetic components by environmental conditions.
Primary immunodeficiency refers to a disorder resulting from a genetic or developmental abnormality in the immune system. Primary immunodeficiency may be classified as follows:
Inherited B cell disorders Due to decreased lymphoid tissue, these cause early infections and mortality. 85% of patients with genetic abnormalities in early B cell development have Btk mutations, which causes X-linked or Bruton's agammaglobulinemia.
Inherited T cell disorders These usually cause recurrent opportunistic yeast infections.
Inherited combined immunodeficiency This affects T and B lymphocytes and can kill infants if untreated. Severe combined immunodeficiency (SCID) is an umbrella term for a group of early-onset illnesses that cause humoral and cellular immune deficiencies and death within a few years. These disorders affect 1 in 50,000 to 100,000 newborns.
Immunodeficiency may also be an acquired condition, due to infections, malignancies and metabolic problems which interfere with the normal synthesis or function of immune cells. Some prominent causes of acquired immunodeficiency include infections with HIV, CMV or measles; blood dyscrasias such as aplastic anaemia or leukaemia; and metabolic disorders such as diabetes mellitus, or renal failure.
Immunodeficiency may result in: – Persistent or recurrent sicknesses, especially infections – Increased risk of certain cancers or tumors
A variety of tests may be necessary to diagnose an immunodeficiency disorder. These include: – Blood complement levels, – HIV testing – Immunoglobin levels – Blood or urine electrophoresis to measure antibody levels and types – White cell count and neutrophil function assays – Cytokine assays following stimulation – Lymphocyte count and proliferation asays
The purpose of treatment is to prevent and treat infectious illnesses. It entails isolation from infected patients or those who have received live vaccinations. In the event of an infection, prompt and aggressive antimicrobial therapy is required, which may necessitate the long-term use of antibiotics or antifungals to prevent reinfection.
Replacement of IgG is required in all B-cell diseases and in the majority of individuals with mixed illnesses. In T-cell diseases, the restoration of immunological function is the objective. With a success rate of 75 to 90 percent, HLA-matched stem cell transplant is the gold standard treatment for newborns with SCID.
Antiviral medications, interferons, and splenectomy are all alternatives that may be advantageous in various circumstances.