RESEARCH - Variation of immunological response in MTX-induced pneumonitis

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Rheumatology Advance Access published online on September 23, 2008

Variation of immunological response in methotrexate-induced pneumonitis

B. Chikura1, N. Sathi2, S. Lane3 and J. K. Dawson2

1Department of Rheumatology, Royal Liverpool University Hospitals,

Liverpool, 2Department of Rheumatology, St Helens Hospital, St Helens

and 3Centre for Medical Statistics for Health, Liverpool University,

Liverpool, UK.

Abstract

Objectives. To assess the variation of peripheral blood and

bronchoalveolar lavage (BAL) inflammatory cell counts and lung biopsy

findings with the degree of exposure to MTX therapy.

Methods. Fifty-six (16 males; 40 females) reported cases of

MTX-induced pneumonitis (MTX-P) on low-dose MTX (5–30 mg) were

identified from a literature search and classified using Searles and

McKendry's criteria. The median cumulative dose was 300 mg and this

was used to categorize patients into low and high MTX-exposure groups

and 6 months was used to divide patients into early- and late-onset

MTX-P groups.

Results. Neutrophil counts in the peripheral blood and BAL were

significantly raised in the low MTX-exposure group compared with the

high MTX-exposure group (P = 0.018 and 0.038, respectively). There

were similar findings when early-onset was compared with late-onset

group. Lymphocytes in BAL were significantly higher in the high

MTX-exposure group compared with low-dose cumulative group (P =

0.007). There were 6 (11%) recorded deaths and all were in the low

MTX-exposure group. Early-onset/low MTX-exposure groups had a high

prevalence of lung fibrosis.

Conclusions. This is the first study to describe the variation of

immunological responses in MTX-P with the degree of exposure to MTX.

Our findings suggest that MTX-P can be divided into two groups: type 1

MTX-P that occurs early, predominated by neutrophils, lung fibrosis

and has a high mortality; and type 2 MTX-P that occurs late,

predominated by lymphocytes, has less lung fibrosis and low mortality.

http://rheumatology.oxfordjournals.org/cgi/content/abstract/ken356v1?papetoc

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