The most common treatment for SCID is bone marrow transplantation, which has been successful using either a matched related or unrelated donor, or a half-matched donor, who would be either parent. The half-matched type of transplant is called haploidentical. Haploidentical bone marrow transplants require the donor marrow to be depleted of all mature T cells to avoid the occurrence of graft-versus-host disease (GVHD). Consequently, a functional immune system takes longer to develop in a patient who receives a haploidentical bone marrow transplant compared to a patient receiving a matched transplant. David Vetter, the original "bubble boy", had one of the first transplantations, but eventually died because of an unscreened virus, Epstein-Barr (tests were not available at the time), in his newly transplanted bone marrow from his sister, an unmatched bone marrow donor. Today, transplants done in the first three months of life have a high success rate. Physicians have also had some success with "in utero" transplants done before the child is born and also by using cord blood which is rich in stem cells. "In utero" transplants allow for the fetus to develop a functional immune system in the sterile environment of the uterus; however complications such as GVHD would be difficult to detect or treat if they were to occur.

More recently gene therapy has been attempted as an alternative to the bone marrow transplant. Transduction of the missing gene to hematopoietic stem cells using viral vectors is being tested in ADA SCID and X-linked SCID. In 1990, four-year-old Ashanthi DeSilva became the first patient to undergo successful gene therapy. Researchers collected samples of DeSilva's blood, isolated some of her white blood cells, and used a retrovirus to insert a healthy adenosine deaminase (ADA) gene into them. These cells were then injected back into her body, and began to express a normal enzyme. This, augmented by weekly injections of ADA, corrected her deficiency. However, the concurrent treatment of ADA injections may impair the success of gene therapy, since transduced cells will have no selective advantage to proliferate if untransduced cells can survive in the presence of the injected ADA.

In 2000, a gene therapy "success" resulted in SCID patients with a functional immune system. These trials were stopped when it was discovered that two of ten patients in one trial had developed leukemia resulting from the insertion of the gene-carrying retrovirus near an oncogene. In 2007, four of the ten patients have developed leukemias. Work aimed at improving gene therapy is now focusing on modifying the viral vector to reduce the likelihood of oncogenesis and using zinc-finger nucleases to more specifically target gene insertion. No leukemia cases have yet been seen in trials of ADA-SCID, which does not involve the "gamma c" gene that may be oncogenic when expressed by a retrovirus.

Trial treatments of SCID have been gene therapy's first success; since 1999, gene therapy has restored the immune systems of at least 17 children with two forms (ADA-SCID and X-SCID) of the disorder.

There are also some non-curative methods for treating SCID. Reverse isolation involves the use of laminar air flow and mechanical barriers (to avoid physical contact with others) to isolate the patient from any harmful pathogens present in the external environment. A non-curative treatment for patients with ADA-SCID is enzyme replacement therapy, in which the patient is injected with polyethyleneglycol-coupled adenosine deaminase (PEG-ADA) which metabolizes the toxic substrates of the ADA enzyme and prevents their accumulation. Treatment with PEG-ADA may be used to restore T cell function in the short term, enough to clear any existing infections before proceeding with curative treatment such as a bone marrow transplant.

Serology (detection on antibodies to a specific pathogen or antigen) is often used to diagnose viral diseases. Because XLA patients lack antibodies, these tests always give a negative result regardless of their real condition. This applies to standard HIV tests. Special blood tests (such as the western blot based test) are required for proper viral diagnosis in XLA patients.

It is not recommended and dangerous for XLA patients to receive live attenuated vaccines such as live polio, or the measles, mumps, rubella (MMR vaccine). Special emphasis is given to avoiding the oral live attenuated SABIN-type polio vaccine that has been reported to cause polio to XLA patients. Furthermore, it is not known if active vaccines in general have any beneficial effect on XLA patients as they lack normal ability to maintain immune memory.

XLA patients are specifically susceptible to viruses of the Enterovirus family, and mostly to: polio virus, coxsackie virus (hand, foot, and mouth disease) and Echoviruses. These may cause severe central nervous system conditions as chronic encephalitis, meningitis and death. An experimental anti-viral agent, pleconaril, is active against picornaviruses. XLA patients, however, are apparently immune to the Epstein-Barr virus (EBV), as they lack mature B cells (and so HLA co-receptors) needed for the viral infection. Patients with XLA are also more likely to have a history of septic arthritis.

It is not known if XLA patients are able to generate an allergic reaction, as they lack functional IgE antibodies.There is no special hazard for XLA patients in dealing with pets or outdoor activities. Unlike in other primary immunodeficiencies XLA patients are at no greater risk for developing autoimmune illnesses.

Agammaglobulinemia (XLA) is similar to the primary immunodeficiency disorder Hypogammaglobulinemia (CVID), and their clinical conditions and treatment are almost identical. However, while XLA is a congenital disorder, with known genetic causes, CVID may occur in adulthood and its causes are not yet understood.

XLA was also historically mistaken as Severe Combined Immunodeficiency (SCID), a much more severe immune deficiency ("Bubble boys").A strain of laboratory mouse, XID, is used to study XLA. These mice have a mutated version of the mouse Btk gene, and exhibit a similar, yet milder, immune deficiency as in XLA.

SCID mice were and still are used in disease, vaccine, and transplant research; especially as animal models for testing the safety of new vaccines or therapeutic agents in people with weakened immune system recessive gene with clinical signs similar to the human condition, also affects the Arabian horse. In horses, the condition remains a fatal disease, as the animal inevitably succumbs to an opportunistic infection within the first four to six months of life. However, carriers, who themselves are not affected by the disease, can be detected with a DNA test. Thus careful breeding practices can avoid the risk of an affected foal being produced.

Another animal with well-characterized SCID pathology is the dog. There are two known forms, an X-linked SCID in Basset Hounds that has similar ontology to X-SCID in humans, and an autosomal recessive form seen in one line of Jack Russell Terriers that is similar to SCID in Arabian horses and mice.

SCID mice also serve as a useful animal model in the study of the human immune system and its interactions with disease, infections, and cancer.

The most common treatment for XLA is an intravenous infusion of immunoglobulin (IVIg, human IgG antibodies) every 3–4 weeks, for life. IVIg is a human product extracted and pooled from thousands of blood donations. IVIg does not cure XLA but increases the patient's lifespan and quality of life, by generating passive immunity, and boosting the immune system. With treatment, the number and severity of infections is reduced. With IVIg, XLA patients may live a relatively healthy life. A patient should attempt reaching a state where his IgG blood count exceeds 800 mg/kg. The dose is based on the patient's weight and IgG blood-count.

Muscle injections of immunoglobulin (IMIg) were common before IVIg was prevalent, but are less effective and much more painful; hence, IMIg is now uncommon.Subcutaneous treatment (SCIg) was recently approved by the U.S. Food and Drug Administration (FDA), which is recommended in cases of severe adverse reactions to the IVIg treatment.

Antibiotics are another common supplementary treatment. Local antibiotic treatment (drops, lotions) are preferred over systemic treatment (pills) for long-term treatment, if possible.One of the future prospects of XLA treatment is gene therapy, which could potentially cure XLA. Gene therapy technology is still in its infancy and may cause severe complications such as cancer and even death. Moreover, the long-term success and complications of this treatment are, as yet, unknown.

The treatment of primary immunodeficiencies depends foremost on the nature of the abnormality. Somatic treatment of primarily genetic defects is in its infancy. Most treatment is therefore passive and palliative, and falls into two modalities: managing infections and boosting the immune system.

Reduction of exposure to pathogens may be recommended, and in many situations prophylactic antibiotics or antivirals may be advised.

In the case of humoral immune deficiency, immunoglobulin replacement therapy in the form of intravenous immunoglobulin (IVIG) or subcutaneous immunoglobulin (SCIG) may be available.

In cases of autoimmune disorders, immunosuppression therapies like corticosteroids may be prescribed.

Bone marrow transplant may be possible for Severe Combined Immune Deficiency and other severe immunodeficiences.

Virus-specific T-Lymphocytes (VST) therapy is used for patients who have received hematopoietic stem cell transplantation that has proven to be unsuccessful. It is a treatment that has been effective in preventing and treating viral infections after HSCT. VST therapy uses active donor T-cells that are isolated from alloreactive T-cells which have proven immunity against one or more viruses. Such donor T-cells often cause acute graft-versus-host disease (GVHD), a subject of ongoing investigation. VSTs have been produced primarily by ex-vivo cultures and by the expansion of T-lymphocytes after stimulation with viral antigens. This is carried out by using donor-derived antigen-presenting cells. These new methods have reduced culture time to 10–12 days by using specific cytokines from adult donors or virus-naive cord blood. This treatment is far quicker and with a substantially higher success rate than the 3–6 months it takes to carry out HSCT on a patient diagnosed with a primary immunodeficiency. T-lymphocyte therapies are still in the experimental stage; few are even in clinical trials, none have been FDA approved, and availability in clinical practice may be years or even a decade or more away.

X-linked SCID is a known pediatric emergency which primarily affects males. If the appropriate treatment such as intravenous immunoglobulin supplements, medications for treating infections or a bone marrow transplant is not administered, then the prognosis is poor. The patients with X-linked SCID usually die two years after they are born. For this reason, the diagnosis of X-linked SCID needs to be done early to prevent any pathogens from infecting the infant.

However, the patients have a higher chance of survival if the diagnosis of X-linked SCID is done as soon as the baby is born. This involves taking preventative measures to avoid any infections that can cause death. For example, David Vetter had a high chance of having X-linked SCID because his elder sibling had died due to SCID. This allowed the doctors to place David in the bubble and prevented infections. In addition, if X-linked SCID is known to affect a child, then live vaccines should not be administered and this can save the infants life. Vaccines, which are pathogens inserted into the body to create an immune response, can lead to death in infants with X-linked SCID. Moreover, with proper treatments, such as a bone marrow transplant, the prognosis is good. The bone marrow transplant has been successful in treating several patients and resulted in a full immune reconstitution and the patient can live a healthy life. The results of bone marrow transplant are most successful when the closest human leukocyte antigen match has been found. If a close match is not found, however, there is a chance of graft-versus-host-disease which means the donor bone marrow attacks the patient's body. Hence, a close match is required to prevent any complications.

Current research is aimed at studying large cohorts of people with CVID in an attempt to better understand age of onset, as well as mechanism, genetic factors, and progression of the disease.

Funding for research in the US is provided by the National Institutes of Health. Key research in the UK was previously funded by the Primary Immunodeficiency Association (PiA) until its closure in January 2012, and funding is raised through the annual Jeans for Genes campaign. Current efforts are aimed at studying the following:

- Causes of complications. Little is known about why such diverse complications arise during treatment

- Underlying genetic factors. Though many polymorphisms and mutations have been identified, their respective roles in CVID development are poorly understood, and not represented in all people with CVID.

- Finding new ways to study CVID. Given that CVID arises from more than one gene, gene knock-out methods are unlikely to be helpful. It is necessary to seek out disease related polymorphisms by screening large populations of people with CVID, but this is challenging given the rarity of the disease.

Once a diagnosis is made, each individual's treatment is based on an individual’s clinical condition. Hematopoietic stem cell transplant is a possible treatment of this condition but its effectiveness is unproven.

Additionally, magnesium supplementation is a promising potential treatment for XMEN. One of the consequences of loss of "MAGT1" function is a decreased level of unbound intracellular Mg2+. This decrease leads to loss of expression of an immune cell receptor called "NKG2D", which is involved in EBV-immunity. Remarkably, Mg2+ supplementation can restore "NKG2D" expression and other functions that are abnormal in patients with XMEN. Early evidence suggests continuous oral magnesium threonate supplementation is safe and well tolerated. Nonetheless, further research is needed to evaluate the use of Mg2+ as a treatment for XMEN. It remains unclear if such supplementation will protect against the development of lymphoma in patients with XMEN. Investigators at the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health currently have clinical protocols to study new approaches to the diagnosis and treatment of this disorder.

Available treatment falls into two modalities: treating infections and boosting the immune system.

Prevention of Pneumocystis pneumonia using trimethoprim/sulfamethoxazole is useful in those who are immunocompromised. In the early 1950s Immunoglobulin(Ig) was used by doctors to treat patients with primary immunodeficiency through intramuscular injection. Ig replacement therapy are infusions that can be either subcutaneous or intravenously administrated, resulting in higher Ig levels for about three to four weeks, although this varies with each patient.

Prognosis depends greatly on the nature and severity of the condition. Some deficiencies cause early mortality (before age one), others with or even without treatment are lifelong conditions that cause little mortality or morbidity. Newer stem cell transplant technologies may lead to gene based treatments of

debilitating and fatal genetic immune deficiencies. Prognosis of acquired immune deficiencies depends on avoiding or treating the causative agent or

condition (like AIDS).

There is no information on birth ratios/rates, but "X-Linked SCID is the most common form of SCID and it has been estimated to account for 46% to 70% of all SCID cases."

There is currently minimal therapeutic intervention available for BENTA disease. Patients are closely monitored for infections and for signs of monoclonal or oligoclonal B cell expansion that could indicate B cell malignancy. Splenectomy is unlikely to reduce B cell burden; peripheral blood B cell counts rose significantly in three patients who underwent the procedure. It remains to be determined whether immunosuppressive drugs, including B cell-depleting drugs such as rituximab, could be effective for treating BENTA disease.

In terms of the management of T cell deficiency for those individuals with this condition the following can be applied:

- Killed vaccines should be used(not "live vaccines" in T cell deficiency)

- Bone marrow transplant

- Immunoglobulin replacement

- Antiviral therapy

- Supplemental nutrition

Gene therapy is a relatively new concept in the field of SCID. This therapy is currently undergoing clinical trial and has cured a small number of children suffering from X-linked SCID and recessive allele SCID. Gene therapy aims to correct the underlying genetic abnormality in SCID. In the case of RD, the genetic abnormality would be AK2 malfunction. Stem cells are taken from an affected child's blood or bone marrow. Then in laboratory conditions the stem cells are manipulated and corrected with gene technology. They are then injected back into the patient. Similarly, in bone transplant, stem cells are able to find their way back through tracking mechanisms.

Treatment consists of immunoglobulin replacement therapy, which replenishes Ig subtypes that the person lack. This treatment is given at frequent intervals for life, and is thought to help reduce bacterial infections and boost immune function. Before therapy begins, plasma donations are tested for known blood-borne pathogens, then pooled and processed to obtain concentrated IgG samples. Infusions can be administered in three different forms: intravenously (IVIg):, subcutaneously (SCIg), and intramuscularly (IMIg).

The administration of intravenous immunoglobulins requires the insertion of a cannula or needle in a vein, usually in the arms or hands. Because highly concentrated product is used, IVIg infusions take place every 3 to 4 weeks. Subcutaneous infusions slowly release the Ig serum underneath the skin, again through a needle, and takes place every week. Intramuscular infusions are no longer widely used, as they can be painful and are more likely to cause reactions.

People often experience adverse side effects to immunoglobulin infusions, including:

- swelling at the insertion site (common in SCIG)

- chills

- headache

- nausea (common in IVIG)

- fatigue (common in IVIG)

- muscle aches and pain, or joint pain

- fever (common in IVIG and rare in SCIG)

- hives (rare)

- thrombotic events (rare)

- aseptic meningitis (rare, more common in people with SLE)

- anaphylactic shock (very rare)

In addition to Ig replacement therapy, treatment may also involve immune suppressants, to control autoimmune symptoms of the disease, and high dose steroids like corticosteroids. In some cases, antibiotics are used to fight chronic lung disease resulting from CVID. The outlook for people varies greatly depending on their level of lung and other organ damage prior to diagnosis and treatment.

SCID mice are routinely used as model organisms for research into the basic biology of the immune system, cell transplantation strategies, and the effects of disease on mammalian systems. They have been extensively used as hosts for normal and malignant tissue transplants. In addition, they are useful for testing the safety of new vaccines or therapeutic agents in immunocompromised individuals.

The condition is due to a rare recessive mutation on Chromosome 16 responsible for deficient activity of an enzyme involved in DNA repair (Prkdc or "protein kinase, DNA activated, catalytic polypeptide"). Because V(D)J recombination does not occur, the humoral and cellular immune systems fail to mature. SCID mice, therefore, present with impaired ability to make T or B lymphocytes, or activate some components of the complement system, and cannot efficiently fight infections, nor reject tumors and transplants.

By crossing SCID mice with mice carrying mutations in related genes, such as interleukin-2Rgamma, more efficient immunocompromised strains can be created to further aid research. The degree to which the various components of the immune system are compromised varies according to what other mutations the mice carry along with the SCID mutation.

The mainstay of treatment consists of thymectomy and immunoglobulin replacement with IVIG (Kelesidis, 2010). Immunodeficiency does not resolve after thymectomy (Arnold, 2015). To treat the autoimmune component of the disease, immune-suppression is sometimes used and it is often challenging to determine if a patient’s symptoms are infectious or autoimmune (Arnold, 2015).

Patients should have serological testing for antibodies to toxoplasma and cytomegalovirus. If receiving a transfusion, CMV negative blood should be used in those with negative serological testing. Live vaccines should also be avoided (Kelesidis, 2010). The CDC recommends pneumococcal, meningococcal, and Hib vaccination in those with diminished humoral and cell-mediated immunity (Hamborsky, 2015).

Some have advocated treating prophylactically with TMP-SMX if CD4 counts are lower than 200 cells/mm^3, similar to AIDS patients (Kelesidis, 2010).

The survival range is estimated to be 3 days to 17 weeks without treatment. Patients die due to bacterial or viral infections. Aggressive treatment with antibiotics is required and bone marrow transplant is common. Patients undergoing bone marrow transplant, specifically from a matched sibling, have a higher 5 year survival rate than those receiving a transplant from other donors.

Treatment for "B cell deficiency"(humoral immune deficiency) depends on the cause, however generally the following applies:

- Treatment of infection(antibiotics)

- Surveillance for malignancies

- Immunoglobulin replacement therapy

Though BLSII is an attractive candidate for gene therapy, bone marrow transplant is currently the only treatment.

The only treatment for Omenn syndrome is chemotherapy followed by a bone marrow transplantation. Without treatment, it is rapidly fatal in infancy.

Treatment in DOCK8 deficiency focuses on preventing and treating infections. Broad-spectrum antibiotics are a common mode of treatment when infection is present, though some infections (like lung abscesses) require surgical treatment. Pneumatocele may be treated with surgery, but the benefit is unclear.

Surgical treatment is also recommended for skin abscesses, along with topical and systemic antibiotics and antifungals.

Long-term treatment with systemic antibiotics, including trimethoprim/sulfamethoxazole, penicillins, and cephalosporins, is effective in preventing skin and lung infections. Other treatments used in DOCK8 deficiency include sodium cromoglycate, which improves white blood cell function, and isotretinoin, which improves skin condition.

Sometimes, Intravenous immunoglobulin is used as a treatment, but its benefits have not been proven. Levamisole is also ineffective. Mixed clinical outcomes have been found with interferon gamma and omalizumab. Though early research on hematopoietic stem cell transplantation was equivocal, later research has shown it to improve immune function. Two patients have been cured by bone marrow transplantation. Cyclosporine A is a current topic of research; preliminary results have shown it to be effective.

Once a diagnosis is made, the treatment is based on an individual’s clinical condition. Based on the apparent activation of the mTOR pathway, Lucas and colleagues treated patients with rapamycin, an mTOR inhibitor. This effectively reduced hepatosplenomegaly and lymphadenopathy, most likely by restoring the normal balance of naïve, effector, and memory cells in the patients’ immune system. More research is needed to determine the most effective timing and dosage of this medication and to investigate other treatment options. Investigators at the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health currently have clinical protocols to study new approaches to the diagnosis and treatment of this disorder.

There are many lymphoproliferative disorders that are associated with organ transplantation and immunosuppressant therapies. In most reported cases, these cause B cell lymphoproliferative disorders; however, some T cell variations have been described. The T cell variations are usually caused by the prolonged use of T cell suppressant drugs, such as sirolimus, tacrolimus, or ciclosporin.