Lipid‐laden alveolar macrophages (LLAM): A useful marker of silent aspiration in children

Abstract

At present there is no test available which identifies children suffering from silent aspiration due to gastroesophageal reflux (GER). The purpose of this study was to determine whether lipid-laden alveolar macrophage (LLAM) scoring is a useful method to arrive at the diagnosis. We evaluated bronchoalveolar lavage fluid (BALF) from 68 children aged 6 months to 14 years (median 3.75 years) for the presence of lipid-laden alveolar macrophages. We compared children with chronic chest disease (CCD) and GER to healthy surgical controls without known lung disease, and to children with recurrent pneumonia without GER. By grading the amount of intracellular Sudan Red-positive material, we determined a semiquantitative lipidladen macrophage (LLAM) score for each patient.Patients with chronic chest disease suspected to be caused by silent aspiration secondary to GER had a significantly higher LLAM score (median, 117; range, 10-956) than children with recurrent pneumonia due to other reasons (median, 29; range, 5-127; P < 0.01) and healthy controls (median, 37; range, 5-188; P < 0.01).We believe that simply observing lipid-laden macrophages is nonspecific, but quantitation of these cells is a useful method for diagnosing silent aspiration in children, especially when the score exceeds 200. Pediatr Pulmonol. 1999; 28:83-88.

The presence of pepsin in the lung and its relationship to pathologic gastro‐esophageal reflux

“…LLMI has been previously shown not to correlate with reflux by pH-MII, but it may be a marker of lung disease severity and has been elevated in patients with asthma, aspiration, lung tumors, and other chronic respiratory diseases. [16][17][18][19][20] In addition, recent studies have suggested that lung injury may result in increased production of pepsinogen C that is produced in the lung, and prior pepsin studies have been potentially confounded by the cross reactivity of the pepsin antibodies in the assay with pepsinogen C; 21,22 we hypothesized that if the LLMI was elevated signifying lung injury, we might falsely see pepsin positivity because of the presence of pepsinogen C. To address this issue, we analyzed four pepsin positive bronchoscopy samples for the presence of pepsinogen A and there was none present in any of the samples suggesting that our assay was detecting pepsin synthesized from the gastrointestinal tract rather than locally synthesized. One possibility to explain the higher LLMI in pepsin positive patients is that pH-MII and endoscopy reflect total reflux burden and that microaspiration may be occurring, even with a normal reflux burden.…”

Committee I: Indications for pulmonary cytology sampling methods

“…A total index is calculated by adding the individual scores. While LLAM can exist in a variety of pulmonary diseases, studies have shown that children suspected of silent gastro-esophageal reflux (GER) have a much higher LLAM index than children with recurrent pneumonia due to other reasons 36 and that the presence of LLAM with at least 10 lipid droplets or 50% cytoplasmic staining was found to be 85% sensitive and 80% specific for GER. 37 Similarly Hopkins et al evaluated LLAM in lung transplant recipients suspected of GER and found that a lipid index of >150 was 82.3% sensitive and 76.4% specific for an abnormal 24 h pH result.…”

Dysphagia and aspiration in children

“…Finally, the LLM index may also vary depending on the amount of time since the last aspiration event 114. Despite all these limitations, a LLM index may provide supporting evidence of aspiration in select patients 115…”