Rapid automated combined in situ hybridization and immunohistochemistry for sensitive detection of cytomegalovirus in paraffin-embedded tissue biopsies.

The authors questioned whether an automated kinetic mode assay of combined cytomegalovirus (CMV) late viral message and immediate and early antigens might result in a more sensitive and timely CMV diagnosis relevant to speedy treatment in the transplant setting. Toward this end, two cohorts were studied using automated in situ hybridization (ISH) for CMV as well as immunohistochemistry (IHC). The first cohort of patients consisted of 19 cases that were histologically positive (CMV-associated cytopathic change). A second cohort consisted of 10 cases that were histologically negative, yet culture positive. From the first cohort of histologically positive cases, 100% were positive by both ISH and IHC run on separate slides. In the second cohort, CMV was detected overall in 70% of cases (50% by ISH alone and 30% by IHC alone). These results indicate that a combined assay of ISH and IHC can detect more cases than routine hematoxylin and eosin staining or either assay alone. In two illustrative cases, used to demonstrate the feasibility of combining ISH and IHC, the authors used a combined two-color assay (ISH and IHC) performed sequentially on the same slide. The combined assays resulted in colocalized single cell message and protein in some cells and demonstrated more positive cells overall (some positive by IHC alone, some by ISH alone, and some by both) than either assay alone. The combined dual color assay can be completed within 4 to 5 hours giving the prospect of a same day result, which is faster than shell vial technique with immunofluorescence (24 to 48 hours) or culture (7 to 14 days). This study demonstrates that combining CMV message and protein assays results in a more sensitive assay and, when carried out in the kinetic mode, allows a speedy result relevant to early anti-CMV therapy.

Analysis of multidrug-resistance (MDR-1) glycoprotein and CD56 expression to separate monoclonal gammopathy from multiple myeloma.

Monoclonal gammopathy of undetermined significance (MGUS) is different from multiple myeloma (MM) by a low proliferation and by its indolent clinical course. In this study, two biological parameters were investigated which mark the transition from MGUS to MM, i.e. expression of the P-170 glycoprotein associated with the multidrug resistance phenotype (MDR-1) and expression of the natural killer cell antigen. CD56. Strong MDR-1 expression was found in plasma cells of 32/38 untreated MGUS as compared with 33/105 untreated MM stage I-III (84% v 32%, P < 0.001) and in 0/10 normal plasma cell samples. CD56 expression in high density was present in 43/57 analysed untreated MM but in none of 23 MGUS (78% v 0%, P < 0.0001). Plasma cells did characteristically show a low Ki-67 proliferation index in 14/15 MGUS patients (mean 0.05%, range 0-0.2%) and a higher index in 25 analysed MM patients (mean 2.31%, range 1-7%, P < 0.03). These data indicate that MDR-1 expression together with absence of CD56 expression and a low proliferation index can be used to separate MGUS from MM.