Neutrophil CD64 for monitoring the activity of nontuberculous mycobacteria infection in patients with rheumatoid arthritis.
OBJECTIVE
To evaluate the utility of neutrophil CD64 as a marker for monitoring the activity of nontuberculous mycobacteria (NTM) infection in patients with rheumatoid arthritis (RA).


METHODS
We compared neutrophil CD64 expression in nine RA patients with NTM infection in the active and inactive phase of NTM disease chronologically. "Active phase" was here defined as present in patients admitted to hospital to receive intensive treatment for NTM, as well as outpatients with an infectious episode showing positive acid- and alcohol-fast bacillus (AFB) staining of sputa (Grade 2-3) who needed to start treatment for NTM with a multiple antibiotics regimen. The cut-off value for CD64 positivity was 2000 molecules/cell.


RESULTS
Neutrophils from patients with active-phase NTM infection expressed high levels of CD64 with a mean ± SEM of 7335 ± 784 molecules/cell. However, during the inactive phase of disease, this was significantly lower (1481 ± 103 molecules/cell, p < 0.001). The sensitivity and specificity of neutrophil CD64 to detect active-phase NTM infection was 96.3% and 84.6%, respectively. Expression of neutrophil CD64 was not affected by disease activity of the RA itself.


CONCLUSIONS
Neutrophil CD64 is useful for monitoring disease activity in NTM infection of patients with RA.
Department of Clinical Laboratory, Sagamihara National Hospital, National Hospital Organization , Kanagawa , Japan.
Akiko
A
Komiya
Toshihiro
T
Matsui
Koichiro
K
Horie
Hidefumi
H
Fukuda
Shinichi
S
Nogi
Kanako
K
Iwata
Hirotaka
H
Tsuno
Hideki
H
Ogihara
Hidekazu
H
Futami
Tatsuoh
T
Ikenaka
Misato
M
Kawakami
Hiroshi
H
Furukawa
Atsushi
A
Hashimoto
Shigeto
S
Tohma
D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000276:immunology* / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009165:Mycobacterium Infections, Nontuberculous / Q000150:complications / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism*; D009170:Nontuberculous Mycobacteria; D017452:Receptors, IgG / Q000378:metabolism*; D012680:Sensitivity and Specificity
D015415:Biomarkers; D017452:Receptors, IgG
CD64; Flow cytometer; Neutrophil; Nontuberculous mycobacteria infections; Rheumatoid arthritis