Tissue transglutaminase (tTG) has recently been identified as the autoantigen recognized by endomysial antibodies in celiac disease (CD) patients and this has permitted the use of an ELISA test to detect the presence in the serum of autoantibodies specific for the diagnosis of CD.
We report two cases of anti-tTG positivity in patients with non-Hodgkin's lymphoma (NHL) without evidence of CD.
Both patients were males aged 67 and 69 years respectively; both were hospitalized for fever and peripheral adenopathy. Lymph node histology showed an immunoblastic high-grade T-cell NHL at the IVth the stage of disease in both cases. They were included in a multicenter study on the association between CD and NHL. Serological screening for CD showed the presence of serum anti-tTG antibodies, with values within the range of those recorded in untreated CD patients in our laboratory; however, both patients had negative anti-endomysial antibodies and in both cases intestinal histology showed normal mucosa with villi and crypts of normal height and depth (villi/crypts ratio > or = 2.5, within the range of normal subjects for our laboratory), and no increase in intraepithelial lymphocytes. The HLA phenotype was obtained giving the following antigens: Case 1: A 3, A 24(9), B 22, B 35, BW 6, DR 1, DR 11(5), DQ 3, DR 52. Case 2: A 2, A 3, B 51(5), B 8, BW 4, BW 6, DR B1*02, DR B1*03, DR B3*01. Both subjects were also positive for serum anti-smooth muscle antibodies and one for antinuclear antibodies.
(1) Serum anti-tTG positivity can be found in subjects with NHL without CD and the real frequency of these 'false positives' must be investigated both in subjects with lymphoproliferative disorders and in patients with autoimmune diseases. (2) In patients with NHL, without CD, anti-tTG positivity may be unassociated with EmA positivity and the biological significance of this finding must be clarified.