P=0.005). There was an inverse correlation with the percentage of gamma/delta T cells in PBL and the TIL median 26.7%). The cells possessing gamma/delta type T cell receptor accounted for a small fraction of concentration (K=−0.3, P<0.05). Conclusions The TIL immunophenotype is diÂerent from the T cells in PBL and TIL (median 5.6% and 3.7%). Tumour-infiltrating T lymphocytes had a significantly PBL and is influenced by the histological grade of the tumour. The activation of TIL and its relationship higher percentage of cells expressing human leucocyte antigen (HLA) DR (median 30.9%) and CD25 (median with tumour progression suggests that they might be sensitized and activated by tumour cells. 6.2%) antigens than the equivalent populations in peripheral blood from the same patient group Keywords Renal cell carcinoma, tumour infiltrating lymphocytes, immunology (P<0.001). The degree of T cell activation appeared ing on the influence of the tumour on lymphoid cells in

We have studied mRNA expression for Class I HLA (human leukocyte antigen) on male germ cells by amplification of gene fragments in PCR technique and by Northern hybridization. RNA was extracted from fractionated gametogenic cells (isolated from testis) and reversely transcribed. Then, cDNA was amplified for specific HLA sequence (HLA, -A, -B, -C). The specificity of this product was confirmed in "nested" PCR of 400 bp gene fragment coding for alpha 2 domain, alpha 3 domain, and the transmembrane portion of Class I HLA. The results indicate minimal expression of classical Class I HLA on gametogenic cells. Northern hybridization with 669 bp cDNA fragment (spanning for alpha 3 domain, transmembrane, cytoplasmic, and 3' untranslated region) resulted in a low intensity signal from gametogenic cell fractions and confirmed our findings obtained by PCR. The minimal expression of classical HLA antigens may create a neutral cover for the male reproductive system, thereby preventing an immunological response during germ cell differentiation.

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Tumour-infiltrating lymphocytes (TIL) and peripheral blood lymphocytes (PBL) from four patients with renal-cell carcinoma (three paired with blood), two colon carcinomas (both paired with blood) and two melanomas (blood was not available) were analysed for the T cell receptor (TCR) delta gene repertoire. Polymerase chain reaction analysis, employing a panel of specific primers for TCR delta gene segments, showed different gene rearrangement patterns in TIL and PBL in all patients. Simultaneous analysis of TIL and PBL revealed the presence of lymphoid cells in the tumour tissue that were not present in the periphery. These results demonstrate that, although tumour-infiltrating lymphocytes contain gamma/delta T cells within the range observed in peripheral blood, these cells differ from those in peripheral blood in their gene repertoire and this may account for selective accumulation or/and in situ amplification of gamma/delta lymphocytes at the tumour site, indicating a unique type of host reaction against tumour.

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