Serum mucin antigen (CASA) as a marker of amiodarone-induced pulmonary toxicity.

Amiodarone is used to treat life-threatening cardiac arrhythmias. Amiodarone-induced pulmonary toxicity (APT) can be difficult to diagnose. APT may result in increased mucus production and mucin expression. Thus, serum mucin-1 was evaluated as a marker for amiodarone-induced pulmonary toxicity. Concentrations of mucin-1 in peripheral blood were determined using cancer-associated serum antigen (CASA) assay in patients taking amiodarone. Eight of ten patients who developed major amiodarone toxicity had high serum CASA levels. Patients with toxicity had a significantly higher mean rank CASA concentration compared with those without major toxicity. CASA shows potential as a marker for amiodarone-induced toxicity, particularly pulmonary toxicity.

IgE+ cells in the peripheral blood of atopic, nonatopic, and bee venom-hypersensitive individuals exhibit the phenotype of highly differentiated B cells.

We have analyzed IgE+ cells in peripheral blood of atopic donors, donors hypersensitive to bee venom, and nonatopic control donors with two- and three-color flow cytometry. Although the percentage of IgE+ cells varied among these groups, the overall phenotypic patterns were similar. Most IgE+ cells do not display typical B-cell markers, such as CD19, CD20, and CD21. A significant proportion of these cells stain for CD38, indicating that they are more differentiated. IgE+ cells express Fc gamma RII and CD45RO, an isoform associated with an advanced level of differentiation. The majority of IgE+ cells do not coexpress other surface immunoglobulin isotypes. In the case of bee venom-hypersensitive donors, we have been able to identify a small population of IgE+ cells with a specificity for phospholipase A2, a major immunogenic component of bee venom. The phospholipase A2+ cells display a phenotype similar to that of the IgE+ cells.

The CD45RO (p180, UCHL1) marker: complexity of expression in peripheral blood.

Analysis of peripheral blood lymphocytes by two- and three-colour high-sensitivity staining with UCHL1 (CD45RO) and other markers shows that the expression of CD45RO on lymphocyte subsets is more complex than is generally supposed. In addition to the populations which express CD45RO and RA in a mutually exclusive manner, up to 30% of cells in adult blood express both markers, at low levels. This "intermediate" population includes CD4-positive cells, and a proportion of these cells express the p55 chain of the IL-2 receptor (CD25), suggesting that they are activated. In cord blood there are few RO-bright cells, but CD45RO is expressed at low intensity on a proportion of cells. Among the CD45RO-bright cells in adult blood at least two subsets can be detected by using MHC Class II and the homing receptor L-selectin as additional markers. This complexity suggests that memory cells are a subset of CD45RO-expressing cells, but that this marker is also found on cells that are activated but not irreversibly "switched" to memory cells.