Immuno 1, Assessing Immune Fxn

Question 1

What happens when the 3 major components (neuts, monos/MO, and complement) of the innate immune system don’t work or are deficient?

Answer 1

1. Neutrophil dysfunction:
   - recurrent, extracellular bacterial infections of skin, lungs, GI tract, and urinary tract
2. Monocyte/MO dysfunction:
   - development of systemic fungal infections, intracellular bacterial infections, chronic viral infections
3. Complement deficiency:
   - recurrent, extracellular bacterial infections of skin, lungs, GI tract, urinary tract

Question 2

What happens when the 3 major components (B cells, CD4 T, CD8 T) of the adaptive immune system don’t work properly, due to dysfunction or decreased numbers of cells?

Answer 2

1. CD4 T deficiency or dysfunction:
   - recurrent and/or disseminated infections with protozoa, fungi, viruses, and intracellular bacteria
2. CD8 T deficiency or dysfunction:
   - recurrent and/or disseminated viral, protozoal, and intracellular bacterial infections
3. B cell deficiency or dysfunction:
   - recurrent, extracellular bacterial infections of skin, lungs, GI, urinary tract

Question 3

What are the most common inherited immune deficiencies of animals?

Dogs, Cats, Equine, Bovine

Answer 3

1. Dogs (rare)
   - CVID (common variable immune deficiency); IgA deficiency
2. Cats (rare)
   - Pelger-Huet anomaly’ Chediak Higashi syndrome
3. Equine
   - SCID (severe combined immune deficiency); IgM
4. Bovine (rare)
   - BLAD (bovine leukocyte adhesion deficiency)

Question 4

What are the typical signs of inherited immune deficiencies?

Answer 4

1. Early age of onset (before 1 yr)
2. Recurrent or chronic bacterial infections
3. Infections that don’t respond to standard therapy
4. Unusual infections (e.g. atypical mycobacteria, disseminated Toxoplasma)

Question 5

How commonly does acquired immune dysfunction in animals?

Dogs, cats, horses, cattle

Answer 5

Acquired immune dysfunction is very COMMON

Dogs: corticosteroid therapy; DM; Cushings

Cats: corticosteroid therapy; FeLV and FIV; FIP infection; DM

Equine: FPT; EIAV infection

Bovine: FPT; BVD infection

Question 6

How can I use information from the CBC and SADP to assess immune function?

Answer 6

• Neuts and lymphs (high and low significant)
• cytologic appearance of lymphs and neuts
• # of monocytes (high is significant)
• globulin concentrations (mostly comprised of IgG)

Question 7

After checking CBC, what is the next set of diagnostic tests for a patient with suspected immune deficiency?

Answer 7

1. Measure serum immunoglobulin conc (IgG, IgA, IgM)

2. Quantitate the number of circulating T cells and B cells (flow cytometry)

Question 8

What about more advanced immune function testing?

Answer 8

• measure complement concentrations
• assess neut and mono respiratory burst and phagocytosis
• assess lymphocyte cytokine production and proliferation
• assess neut and mono chemotaxis

Question 9

If you diagnose inherited immune deficiency, is there anything you can do about it?

Answer 9

1. Humoral immune deficiency (CVID; B cell deficiency)
   - administer periodic plasma or WB transfusions
   - administer hyperimmune globulin (e.g. high-titered parvo serum)
   - aggressive, but short-term rotating program of antimicrobial therapy
   - use probiotics or trans-faunation to displace pathogenic bacteria in the gut
2. Complement deficiency:
   - administer fresh or fresh frozen plasma transfusion
3. CD4 T deficiency:
   - administer non-specific immune stimulants to induce IFN-gamma production
4. CD8 T deficiency:
   - administer immune stimulants to boost NK cell fxn (can substitute for CD8 cells)