Complete or partial deficiency

- "Complete insufficiency" of T cell function can result from hereditary conditions (also called primary conditions) such as severe combined immunodeficiency (SCID), Omenn syndrome, and cartilage–hair hypoplasia.

- "Partial insufficiencies" of T cell function include acquired immune deficiency syndrome (AIDS), and hereditary conditions such as DiGeorge syndrome (DGS), chromosomal breakage syndromes (CBSs), and B-cell and T-cell combined disorders such as ataxia-telangiectasia (AT) and Wiskott–Aldrich syndrome (WAS).

- "Primary (or hereditary) immunodeficiencies" of T cells include some that cause complete insufficiency of T cells, such as severe combined immunodeficiency (SCID), Omenn syndrome, and Cartilage–hair hypoplasia.

- "Secondary causes" are more common than primary ones. Secondary (or acquired) causes are mainly:

Presentations differ among causes, but T cell insufficiency generally manifests as unusually severe common viral infections (respiratory syncytial virus, rotavirus), diarrhea, and eczematous or erythrodermatous rashes. Failure to thrive and cachexia are later signs of a T-cell deficiency.

A minority of patients are diagnosed with thymoma prior to manifestation of the immunodeficient state. Spindle-cell histology is present in most cases.

Because patients with GS have deficient humoral and cellular immunity, they are susceptible to a wide range of infections. Most commonly these patients suffer from respiratory tract infections. Chronic diarrhea is often related to villous atrophy rather than infection (Kelesidis, 2010).

Often autoimmune disease is associated with GS - most commonly pure red cell aplasia and myasthenia gravis. While the patients may experience hypogammaglobulinemia, a large percentage will have autoantibodies present in their serum (Kelesidis, 2010). It is theorized that the presence of thymoma may inhibit the thymus’s normal role in production of self-tolerant T lymphocytes. These T-lymphocytes may then attack the B cell precursors in the marrow, preventing maturation and ultimately resulting in hypogammaglobulinemia (Arnold, 2015).

Immunodeficiency (or immune deficiency) is a state in which the immune system's ability to fight infectious disease and cancer is compromised or entirely absent. Most cases of immunodeficiency are acquired ("secondary") due to extrinsic factors that affect the patient's immune system. Examples of these extrinsic factors include HIV infection, extremes of age, and environmental factors, such as nutrition. In the clinical setting, the immunosuppression by some drugs, such as steroids, can be either an adverse effect or the intended purpose of the treatment. Examples of such use is in organ transplant surgery as an anti-rejection measure and in patients suffering from an overactive immune system, as in autoimmune diseases. Some people are born with intrinsic defects in their immune system, or primary immunodeficiency. A person who has an immunodeficiency of any kind is said to be immunocompromised. An immunocompromised person may be particularly vulnerable to opportunistic infections, in addition to normal infections that could affect everyone. Immunodeficiency also decreases cancer immunosurveillance, in which the immune system scans the body's cells and kills neoplastic ones.

There are no formal diagnostic criteria (Kelleher, 2003) and many informal definitions exist. Most commonly thymoma is present with mixed humoral and cellular immune deficiency. T and B cells are both depleted so patients suffer from both encapsulated organisms as well as opportunistic infections (Miyakis, 2005). Some have defined GS as a subset of common variable immunodeficiency (CVID). Unlike CVID, there are reduced B cells in the periphery in GS (Kelesidis, 2010).

More generally it can be defined as an adult-onset primary immunodeficiency associated with thymoma, hypogammaglobulinemia, diminished B and T cells, and inverted CD4/CD8+ ratio(Kelesidis, 2010).

Lymphoproliferative disorders (LPDs) refer to several conditions in which lymphocytes are produced in excessive quantities. They typically occur in people who have a compromised immune system. They are sometimes equated with "immunoproliferative disorders", but technically lymphoproliferative disorders are a subset of immunoproliferative disorders, along with hypergammaglobulinemia and paraproteinemias.

Combined immunodeficiencies (or combined immunity deficiency) are immunodeficiency disorders that involve multiple components of the immune system, including both humoral immunity and cell-mediated immunity.

This category includes conditions such as bare lymphocyte syndrome, as well as severe combined immunodeficiency.

ICD-9 divides immune deficiencies into three categories: humoral (279.0), cell-mediated (279.1), and combined (279.2). However, ICD-10 does not include a category for cell-mediated immune dysfunction (antibody is D80, and combined is D81), thus grouping T-cell mediated conditions with combined conditions.

Lymphoproliferative disorders are a set of disorders characterized by the abnormal proliferation of lymphocytes into a monoclonal lymphocytosis. The two major types of lymphocytes are B cells and T cells, which are derived from pluripotent hematopoetic stem cells in the bone marrow. Individuals who have some sort of dysfunction with their immune system are susceptible to develop a lymphoproliferative disorder because when any of the numerous control points of the immune system become dysfunctional, immunodeficiency or deregulation of lymphocytes is more likely to occur. There are several inherited gene mutations that have been identified to cause lymphoproliferative disorders; however, there are also acquired and iatrogenic causes.

Isolated primary immunoglobulin M deficiency (or selective IgM immunodeficiency (SIgMD)) is a poorly defined dysgammaglobulinemia characterized by decreased levels of IgM while levels of other immunoglobulins are normal. The immunodeficiency has been associated with some clinical disorders including recurrent infections, atopy, Bloom's syndrome, celiac disease, systemic lupus erythematosus and malignancy, but, surprisingly, SIgMD seems to also occur in asymptomatic individuals. High incidences of recurrent upper respiratory tract infections (77%), asthma (47%) and allergic rhinitis (36%) have also been reported. SIgMD seems to be a particularly rare antibody deficiency with a reported prevalence between 0.03% (general population) and 0.1% (hospitalized patients).

The cause of selective IgM deficiency remains unclear, although various mechanisms have been proposed, such as an increase in regulatory T cell functions, defective T helper cell functions and impaired terminal differentiation of B lymphocytes into IgM-secreting cells among others. It is however puzzling that class switching seems to happen normally (serum levels of other antibodies are normal), while dysfunctioning of IgM synthesis is expected to occur together with abnormalities in other immunoglobulins. Notwithstanding a clear pathogenesis and commonly accepted definition, a cutoff for SIgMD could be the lower limit of the serum IgM reference range, such as 43 mg/dL in adults or even 20 mg/dL.

In reality, immunodeficiency often affects multiple components, with notable examples including severe combined immunodeficiency (which is primary) and acquired immune deficiency syndrome (which is secondary).

A range of disorders can cause decreases in white blood cells. This type of white blood cell decreased is usually the neutrophil. In this case the decrease may be called neutropenia or granulocytopenia. Less commonly, a decrease in lymphocytes (called lymphocytopenia or lymphopenia) may be seen.

Atypical infections are the key clinical manifestation of SGD. Within the first few years of life, patients will experience repeated pyogenic infections by species such as "Staphylococcus aureus", "Pseudomonas aeruginosa" or other Enterobacteriaceae, and "Candida albicans". Cutaneous ulcers or abscesses and pneumonia and chronic lung disease are common. Patients may also develop sepsis, mastoiditis, otitis media, and lymphadenopathy. Infants may present with vomiting, diarrhea, and failure to thrive.

Diagnosis can be made based upon CEBPE gene mutation or a pathognomonic finding of a blood smear showing lack of specific granules. Neutrophils and eosinophils will contain hyposegmented nuclei (a pseudo-Pelger–Huet anomaly).

CD25 deficiency or interleukin 2 receptor alpha deficiency is an immunodeficiency disorder associated with mutations in the interleukin 2 receptor alpha (CD25) (IL2RA) gene. The mutations cause expression of a defective α chain or complete absence thereof, an essential part of high-affinity interleukin-2 (IL-2) receptors. The result is a syndrome described as IPEX-like or a SCID.

In one patient, deficiency of CD25 on CD4+ lymphocytes caused significantly impaired sensitivity to IL-2. This was demonstrated by a lack of measurable response in anti-inflammatory interleukin-10 (IL-10) secretion to low-dose IL-2 incubation. Greatly reduced IL-10 secretion compared to healthy humans results in a syndrome comparable to IPEX syndrome, a type of autoimmunity which is caused by FoxP3 transcription factor dysfunction. In addition to IPEX-like symptoms, CD25 deficiency increases susceptibility to viral infections and possibly fungal and bacterial infections.

As IL-2 is an important inducer of lymphocyte proliferation, the absence of highly sensitive IL-2 receptors may also significantly hinder activation and clonal expansion of CD8+ and CD4+ lymphocytes and NK cells. One case also reported the absence of CD1, a MHC-like glycoprotein involved in the presentation of lipid antigens to T cells, in a CD25 deficient patient. Furthermore, chronic upregulation of anti-apoptotic Bcl-2 in thymocytes was also described possibly allowing autoreactive T cells to escape deletion.

Neutropenia can be acquired or intrinsic. A decrease in levels of neutrophils on lab tests is due to either decreased production of neutrophils or increased removal from the blood. The following list of causes is not complete.

- Medications - chemotherapy, sulfas or other antibiotics, phenothiazenes, benzodiazepines, antithyroids, anticonvulsants, quinine, quinidine, indomethacin, procainamide, thiazides

- Radiation

- Toxins - alcohol, benzenes

- Intrinsic disorders - Fanconi's, Kostmann's, cyclic neutropenia, Chédiak–Higashi

- Immune dysfunction - disorders of collagen, AIDS, rheumatoid arthritis

- Blood cell dysfunction - megaloblastic anemia, myelodysplasia, marrow failure, marrow replacement, acute leukemia

- Any major infection

- Miscellaneous - starvation, hypersplenism

Symptoms of neutropenia are associated with the underlying cause of the decrease in neutrophils. For example, the most common cause of acquired neutropenia is drug-induced, so an individual may have symptoms of medication overdose or toxicity.

Treatment is also aimed at the underlying cause of the neutropenia. One severe consequence of neutropenia is that it can increase the risk of infection.

The International Union of Immunological Societies recognizes nine classes of primary immunodeficiencies, totaling over 120 conditions. A 2014 update of the classification guide added a 9th category and added 30 new gene defects from the prior 2009 version.

The precise symptoms of a primary immunodeficiency depend on the type of defect. Generally, the symptoms and signs that lead to the diagnosis of an immunodeficiency include recurrent or persistent infections or developmental delay as a result of infection. Particular organ problems (e.g. diseases involving the skin, heart, facial development and skeletal system) may be present in certain conditions. Others predispose to autoimmune disease, where the immune system attacks the body's own tissues, or tumours (sometimes specific forms of cancer, such as lymphoma). The nature of the infections, as well as the additional features, may provide clues as to the exact nature of the immune defect.

LAD was first recognized as a distinct clinical entity in the 1970s. The classic descriptions of LAD included recurrent bacterial infections, defects in neutrophil adhesion, and a delay in umbilical cord sloughing. The adhesion defects result in poor leukocyte chemotaxis, particularly neutrophil, inability to form pus and neutrophilia.

Individuals with LAD suffer from bacterial infections beginning in the neonatal period. Infections such as omphalitis, pneumonia, gingivitis, and peritonitis are common and often life-threatening due to the infant's inability to properly destroy the invading pathogens. These individuals do not form abscesses because granulocytes cannot migrate to the sites of infection.

Hypogammaglobulinemia is a type of primary immunodeficiency disease in which not enough gamma globulins exist in the blood (thus "" + "gamma" + "globulin" + ""). This entails that not enough antibodies exist, which impairs the immune system. Hypogammaglobulinemia is a characteristic of common variable immunodeficiency.

causes:

nephrotic syndrome

Neutrophils are the primary white blood cells that respond to a bacterial infection, so the most common cause of neutrophilia is a bacterial infection, especially pyogenic infections.

Neutrophils are also increased in any acute inflammation, so will be raised after a heart attack, other infarct or burns.

Some drugs, such as prednisone, have the same effect as cortisol and adrenaline (epinephrine), causing marginated neutrophils to enter the blood stream. Nervousness will very slightly raise the neutrophil count because of this effect.

A neutrophilia might also be the result of a malignancy. Chronic myelogenous leukemia (CML or chronic myeloid leukaemia) is a disease where the blood cells proliferate out of control. These cells may be neutrophils. Neutrophilia can also be caused by appendicitis and splenectomy.

Primary neutrophilia can additionally be a result of Leukocyte adhesion deficiency.

A lymphocyte is one of the subtypes of white blood cell in a vertebrate's immune system. Lymphocytes include natural killer cells (Phagocytes) (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity). They are the main type of cell found in lymph, which prompted the name "lymphocyte".

Signs and symptoms of neutropenia include fever, painful swallowing, gingival pain, skin abscesses, and otitis. These symptoms may exist because individuals with neutropenia often have infection

Children may show signs of irritability, and poor feeding. Additionally, hypotension has also been observed in individuals who suffer from this condition

Neutrophilia (also called neutrophil leukocytosis or occasionally neutrocytosis) is leukocytosis of neutrophils, that is, a high number of neutrophil granulocytes in the blood.

Treatment is by parenteral administration of gamma globulins, either monthly intravenously, or, more recently, by weekly self-administered hypodermoclysis. In either case, mild allergic reactions (generalized pruritus, urticaria) are common, and are usually manageable with oral diphenhydramine.

Neutropenia or neutropaenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteria, bacterial fragments and immunoglobulin-bound viruses in the blood. Patients with neutropenia are more susceptible to bacterial infections and, without prompt medical attention, the condition may become life-threatening (neutropenic sepsis).

Neutropenia can be acute (temporary) or chronic (long lasting). The term is sometimes used interchangeably with "leukopenia" ("deficit in the number of white blood cells").

WHIM Syndrome (or Warts, Hypogammaglobulinemia, Immunodeficiency, and Myelokathexis syndrome) is a rare congenital immunodeficiency disorder characterized by chronic noncyclic neutropenia.