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Tests of intestinal permeability are used as a reflection of upper-small-intestinal mucosal damage. Thirty-two elderly in-patients aged 75-96 years, and 64 hospital volunteers aged 22-64 years with no overt gastro-intestinal disease were studied to determine whether permeability changes with increasing age. Intestinal permeability was assessed by measuring the 5-h urinary excretion of a monosaccharide, L-rhamnose, and a disaccharide, cellobiose, for 5 h after their oral administration in a hypertonic solution. While in the elderly, excretion of both mono- and di-saccharides was significantly reduced by a half to two-thirds, the ratio of the two sugars in the urine was similar in both age groups. We conclude that permeability was unimpaired in the elderly patients whom we studied. Because the test depends on a ratio of excretion rates rather than an absolute rate, accuracy of urine collection and abnormal renal function do not invalidate the results. It is therefore useful as a screening test of upper-small-intestinal mucosal damage in the elderly.

SUMMARYWe have isolated, from an individual patient with metastatic melanoma, a series of eight TIL clones capable of lysing autologous melanoma cell targets. Six of the eight clones expressed TCRAV2S1 and lysed targets expressing HLA-A2 and the Melan-A/MART-1 peptide: AAGIGILTV. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis showed that the Melan-A/ MART-1-specific clones were predominant in the bulk culture prior to cloning. However, the tumour progressed in vivo even in the presence of these tumour cell-lytic clones. Using the antiMelan-A/MART-1 MoAb (A-103), we noted that Melan-A/MART-1 expression on three melanoma cell lines varied considerably during in vitro culture, in the absence of T cell immunoselection, relative to cell density. Tumour cells which spontaneously decreased Melan-A/MART-1 expression were less susceptible to specific TIL lysis. Melan-A/MART-1 expression and susceptibility to lysis increased in cells cultured at lower density. These data suggest that modulation of tumour antigen may account for tumour progression in the presence of tumour cell-lytic T lymphocytes. The observations suggest a possible explanation for the common finding of Melan-A/MART-1-specific lytic TIL in clinically progressing melanomas, as well as a possible pathway for therapeutic intervention.

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To assess the effect of urinary infection on a typical double-sugar test of intestinal permeability, rhamnose and cellobiose were added to 12 infected urine samples to give sugar concentrations generally present in the 5-h urine samples of patients undergoing the test. Rhamnose concentration fell by approximately 20% in two of the specimens after incubation at 37 degrees C for 5 h. Eight of the 12 samples showed a fall in cellobiose concentration at 2.5 h, and 11 at 5 h. On five occasions more than 90% of the cellobiose was destroyed within 5 h. Yet only eight of these urine samples contained organisms that were able to metabolize cellobiose. This apparent anomaly may have resulted from bacteria surviving in spite of the thiomersal preservative, and then consuming the glucose to which the cellobiose was hydrolysed to enable calculation of cellobiose concentration. We conclude that bacteriuria may invalidate the result of the double-sugar test of intestinal function.

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