Cytoplasmic cytomegalovirus inclusions in human bile duct epithelia

HUMAN PATHOLOGY

Volume 18, No. 9 [September 1987]

Endocytosis of Immunoglobulin Heavy a n d Light Chains by M e l a n o m a Cells

To the Edilor:--I write to report the finding that melanoma cells of the epithelioid type seem to contain heavy and light chain immunoglobulins, especially IgG and ~ and h chains. While immunostaining a lymph node having metastasis of a melanoma to show thepresence of IgG, ~, and h chains in plasma cells, we found that the cytoplasm of the melanoma cells also presented an intense staining (fig. 1). This striking result was considered an artifact, and various controls were applied in an attempt to explain this staining. Controls used included endogenous peroxidase and pseudoperoxidase activity blockage; nonspecific ionic binding blockage with increased strength of the bufferl.~; destruction of free aldehyde groups that might have been introduced by fixation by previous incubation with sodium borohydridea; use of Tris buffer saline in substitution for the primary antiserum; and absorption of the antisera with the corresponding antigens. All these controls, together with a series of dilutions of primary antisera that resulted in positive staining after dilutions as high as 1:8,000, seemed to indicate that the immunostaining was due to tile immunizing antigens and not to an artifact. 4 We then had to consider the interpretation that these immunoglohulins 'might he present in tile cytoplasm of melanoma cells. We thought that although in situ synthesis by neoplastic derepression of the appropriate g.enes was difficult to accept, considering the great elaboratmn and complication of such a synthesis, absorption of circulating immunoglobulins by endocytosis could be a rea-

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sonable explanation. Double staining of two different antigens in the same section, with coincident staining in the same cell, seemed to support the second interpretation. We believe that pathologists working in immunocytochemical diagnosis ought to know of this as well as other possibilities of unexpected immunostaining that might confuse the final interpretation of results. CLAUDIO ~IONTERO, M D

DOLORES I. SEGURA, MD Hospital "Virgen del Rocio" Sevilla, Spain 1. Capel PJA: Histochemical use of borohydrides as aldehyde blocking reagents.J Immunol Meth 5:165, 1974 2. Grube D: Immunoreactivities of gastrin (G-) cells: II. Non-specific binding of immunoglobulins to G-cells by ionic interactions. Histochemistry 66:149, 1980 3. Lillie RD, Pizzolato P: A quantitative immunofluorescence method based on the covalent coupling of protein to Sepharose beads. Stain Tech 47:13, 1972 4. Sternberger L: lmmunocytochemistry, ed 3. New York, John Wiley & Sons, 1986, p 232

Cytoplasmic Cytomegalovirus Inclusions in Human Bile Duct Epithelia

To the Editor:--I read with great interest the recent article by Gorelkin et aL l onstaining qualities and ultrastructural observations of cytomegalovirus inclusions. The authors emphasize the practical importance in diagnosis of the infection. Uhrastructural descriptions of human cells infected with cytomegalovirus have been rare. ~,~ We have studied the ultrastructure of the liver in two cases of congenital cytomegalovirus hepatitis, one of which has been reported previously. 4 Tile characteristic inclusions were found in the bile duct epithelial cells (fig. IA). We were able to study the process of formation of cytoplasmic inclusions. T h e infected cells contained extensive Golgi zones (fig. 1B). Vacuoles with one of two viruses had become detached from the Golgi zones. The vacuoles had fused, giving rise to extensive cytoplasmic inclusions (fig. IC). Our finding supports the statement of Gorelkin et al) that globular intracytoplasmic inclusions represent vacuoles containing mature virions. M A R T H A BALAZS, h i D

Department of Pathology Jfinos Hospital , Budapest, Hungary

F I G U R E 1 [Montero]. General overview of a lymph node metastasis of a melanoma. Simultaneous demonstration of X and K chains in the same section, with Papanicolaou's method, using a sequence that reveals the first antigen with diaminobenzidine and the second one with 4-chloro-l-naphthol. There is a suPerimposition of colors [brown and blue-black] in the same cell in the original slide9[ x 78.} In,el, Magnification of the cell grouP marked with an arrowhead. [ x 312.}

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1. Gorelkin L, Chandler'FW, Ewing EP: Staining qualities of cytomegalovirus inclusions in the lungs of paticnts with the acquired immunodeficiency syndrome: a potential sourcc of diagnostic misinterpretation. HUM P^THOL 17:926, 1986 2. Donnellan WL, Cantra-Umporn S, KiddJM: Tile cytomegalic inclusion cell: an electron microscopic stud)'. Arch Pathol 82:335, 1965 3. Martin AM, Kurtz SM: Cytomegalovirus disease: an electron microscopic histochemical study of the virus at necropsy. Arch Pathol 82:27, 1966 4. Bal,~zs M: Electron microscopic examination of congenital cytomegalovirus hepatitis. Virchows Arch [A] 405:119, 1984

CORRESPONDENCE

FIGURE 1 (Ba167_s]. A, Electron mlcrograph of a cytomegaIovirus-lnfected bile duct epithelial cell. Inset, Enlarged bile duct epithelial cell with intranuclear inclusion and coarse cytoplasmic granularity. [Hematoxylin-esoin stain.) B, Mature virus particles near the Golgi zone (Go). C, Fusion of vacuoles containing mature virions [arrows). (Original magnification: A, x 8,250, inset, x 280; B, 12.500; C, 40,000.)

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