Association between mixed cryoglobulinemia, translocation (14;18), and persistence of occult HCV lymphoid infection after treatment

To the Editor:

We read with interest the article by Sansonno et al.,1 who investigated 16 consecutive patients with hepatitis C virus (HCV)-positive chronic liver disease, including 8 with lymphoproliferative disorders (LPDs): 5 with mixed cryoglobulinemia (MC) (3 with type II), and 3 with monoclonal gammopathy of undetermined significance (MGUS). Translocation (14;18) was not detected in peripheral blood mononuclear cells (PBMCs), single portal tract inflammatory infiltrates, or liver biopsy sections. In spite of the small number of patients tested, this study offers interesting data with regard to the accurate analysis of t(14;18)-negative MC patients. In fact, t(14;18) was previously shown to be significantly associated with MC—especially type II—in several reports over the last 9 years using polymerase chain reaction–based methods and fluorescence in situ hybridization.2–9 Translocation (14;18) was detected in the PBMCs of HCV-positive patients in 99 of 364 (27.2%) without LPDs and in 85 of 151 (56.3%) with LPDs, including 78 of 128 (60.9%) with MC and 7 of 23 (30.4%) with B cell non-Hodgkin's lymphoma (NHL). No association was reported between t(14;18) and MGUS. In type II MC (the form possibly evolving in NHL), t(14;18)-positive B cells were also shown to be clonally expanded and characterized by altered Bcl-2/Bax ratio, indicating their expanded life.6 Furthermore, these clones may regress following antiviral treatment and expand again after viral relapse.6, 7 Bcl-2 overexpression was also shown in the bone marrow and liver infiltrates of MC patients, as well as in 1 case of HCV-positive, t(14;18)-negative MC.10

Overall, the available data strongly suggest that Bcl-2–related expanded B cell life is important in the pathogenesis of MC and possibly other HCV-related LPDs, and that t(14;18) may represent, in most cases, a key factor. In the study by Sansonno et al.,1 neither t(14;18) nor Bcl-2 overexpression were detected, and the hypothesis that the challenge of liver lymphoid infiltrates with viral epitopes represents the key factor in MC pathogenesis was suggested.

In this respect, data we recently obtained may be of interest. We analyzed 9 consecutive HCV-positive patients with MC who showed sustained virological response after treatment. An extensive follow-up showed persistent HCV RNA negativity both in serum and liver samples via very sensitive detection methods (Table 1). In contrast, mitogen-stimulated11 and uncultured PBMCs were HCV RNA–positive in 5 cases (Table 1). Detection of negative-strand HCV RNA via Tth-based reverse-transcriptase polymerase chain reaction confirmed active cell infection in most cases. Interestingly, isolated lymphatic infection was strictly associated with the persistence of both MC-syndrome and t(14;18)-bearing B cell clones (Table 1). On one hand, these data confirm the frequent association between t(14;18) and MC in our geographic area. On the other hand, they strongly suggest that the pathogenesis of MC is not necessarily related to the intrahepatic challenge between HCV epitopes and lymphoid infiltrates. Further studies investigating the possible role played by lymphatic infection in HCV is important.

Table 1. Detection of HCV RNA in Serum, Liver, and Peripheral Blood Mononuclear Cells and Determination of t(14;18)-Carrying B Cell Clones in 9 Mixed Cryoglobulinemia Patients Followed up After Response to Antiviral Therapy

Patient No.	Age (Years)/Sex	Cryoglobulins (Type/Cryocrit %)	Posttreatment Follow-up*
			Months of Follow-up	HCV RNA†			t(14;18)	MC Syndrome
				Serum	Liver	PBMCs
Abbreviations: HCV, hepatitis C virus; PBMCs, peripheral blood mononuclear cells; MC, mixed cryoglobulinemia; F, female; M, male; IgG, immunoglobulin G; IgM, immunoglobulin M; (−), negative; (+), positive. * Positive results of HCV RNA and t(14;18) tests were confirmed in at least 3 samples taken at different times during follow-up. In t(14;18)-positive cases, bcl-2/JH junction sequences showed identity between pretreatment and posttreatment (follow-up) translocated B cell clones. † HCV RNA was detected via “homemade” nested one-tube reverse-transcriptase polymerase chain reaction followed by Southern hybridization (sensitivity: 1-5 IU/mL) and via transcription-mediated amplification (TMA; Bayer Diagnostics, Tarrytown, NY) (sensitivity: <5 UI/mL).
1	64/F	IgG-IgMκ/11%	52	(−)	(−)	(+)	(+)	(+)
2	45/F	IgG-IgMκ/3%	56	(−)	(−)	(+)	(+)	(+)
3	63/F	IgG-IgMκ/8%	40	(−)	(−)	(−)	(−)	(−)
4	50/F	IgG-IgM(κ + λ)/10%	37	(−)	(−)	(−)	(−)	(−)
5	47/M	IgG-IgMκ/14%	44	(−)	(−)	(−)	(−)	(−)
6	41/M	IgG-IgMκ/3%	30	(−)	(−)	(+)	(+)	(+)
7	50/F	IgG-IgMκ/7%	33	(−)	(−)	(−)	(+)	(−)
8	46/M	IgG-IgMκ/2.5%	90	(−)	(−)	(+)	(−)	(−)
9	42/M	IgG-IgMκ/3.5%	53	(−)	(−)	(+)	(+)	(+)

In conclusion, available data suggest that MC and other HCV-related LPDs recognize different pathogenetic pathways leading to a similar clinical picture. An accurate understanding of these different pathways, as well as the frequency of their involvement in the pathogenetic mechanisms, is essential for the correct appraisal of both therapeutic and preventive measures.

Carlo Giannini Ph.D.*, Francesca Giannelli Ph.D.*, Anna Linda Zignego M.D., Ph.D.*, * Department of Internal Medicine, Center for Systemic Manifestations of Hepatitis Viruses, University of Florence, Florence, Italy.