Phagocytic system disorders

Do you remember Pacman? the golden circle eating ghosts? well imagine if you can eat this ghosts but won't be able to digest them. 

Well in Chronic Granulomatous disease (a.k.a. Bridges–Good syndrome, Chronic granulomatous disorder, and Quie syndrome or CGD), our phagocytic system (neutrophils and monocytes) can EAT but CAN'T DIGEST (the catalase positive organisms). Was discovered first in 1950 in Minesota but described and named later in 1957

Why they can't digest? well due to a defect in forming reactive oxygen compounds (specially superoxide radical) needed to kill the catalase positive organisms. 

To remember this organisms, I found a nmemonic that might be useful: SPACE

Staph

Pseudomona aeroginosa

Aspergillus

Candida

Enterobacteriaceae (Klebsiella and Serratia)

Like the other immune disorders, patients will present with recurrent infections like: pneumonia, abscesses of the skin, tissues, osteomyelitis, bacteremia/fungemia and superficial skin infections such as cellulitis or impetigo. 

How to diagnosis? clasically is using the nitroblue-tetrazolium (NBT) test which is NEGATIVE in CGD (we are used to have positive test for diseases, but in this case negative test means disease...remember that), so if the nitroblue doesn't turn blue is negative, and the opposite if it's blue is positive meaning an adequate production of reactive oxygen products. Other test used is  the dihydrorhodamine (DHR) test where blood is mixed with DHR, incubated, and then is stimulated to produce superoxide radicals.

Do we have associations? well yes, if we go back to the name CGD = "granulomatous", we will find formation of granulomas, which can obstruct in different levels as pyloric, bladder, urethra and intestinal. 

And finally talking about the treatment, we might need to give antibiotics as prophylactics, also the use of interferon gamma 1b which will increase the immune system capacity to fight against infections, and as last treatment we have the hematopoietic stem cell transplat (which is the only known cure).

So, in summary, remember our system can eat but can't digest, remember the catalase positive organisms (SPACE), remember how to diagnosis it using either the NBT or DHR tests, the granulomas formation and finally remember the treatment (stem cell transplant)

Hope you enjoy this topic, the next one will be about combined immunodeficiencies which will be the last of this immune diseases.

See you on the next post,

Carlos Albrecht