Summary Despite the presence of a lymphocytic infiltrate in solid cancers, the failure for tumour growth to be contained suggests an inadequate immune response to the tumour. Poor cytotoxicity exerted by tumour-infiltrating lymphocytes (TILs) against tumour cells in vitro, combined with continued tumour growth in vivo, suggests deficiencies in TIL function or numbers. Various theories have been postulated to explain how tumour cells may escape immunosurveillance and control. One of the many hypotheses is the failure of production of cytokines, which are necessary for T cells to mediate their function. Thus, the expression of cytokine mRNA in human breast tumour sections was investigated by reverse transcriptase polymerase chain reaction (RT-PCR) with cytokine-specific primers. A relatively consistent finding was detection of interleukin (IL) 10 mRNA among the tumours. No IL-2 and little IL-4 mRNA was detected in the tumours. IL-6 and IL-10 mRNA was detected in only one and two of the normal breast tissues respectively. IL-2, IL-4 and tumour necrosis factor (TNF)-a mRNA was not detected in any of the normal breast tissues. The reduced function of TILs may be related to IL-10, which has known inhibitory effects on T-cell activation.

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Monoclonal antibodies made against lymphocyte differentiation antigens were used to characterize phenotypically the lymphoid cell subpopulations in sections of human lymphoid tissue and inflamed gingival tissue associated with the deciduous dentition in children. Four monoclonal antibodies designated FMC 1, FMC 4, FMC 7, and UCHT1 were used. These antibodies are specific for B‐cells, p28,33 (la‐like) antigen, a B‐cell subset, and peripheral T‐cells respectively. FMC 1 and FMC 4 positive cells (B‐cells) were found mainly in the secondary follicles while UCHT1 positive cells (T‐cells) were found in the parafollicular areas of human tonsils. Cells in some, but not all, secondary follicles in the tonsils were FMC 7 positive. In the gingival tissue only 12.6 % of the infiltrating cells were FMC 1 positive, 12.2 % were FMC 4 positive, and 4.8 % FMC 7 positive. On the other hand over 75 % of cells appeared to be UCHT1 positive. These results indicate that the majority of inflammatory cells in gingivitis associated with the deciduous dentition in children have the phenotype B‐cell antigen‐/p28,33 (lalike) antigen‐/B‐cell subset antigen‐ and possibly T‐cell antigen+. Such a phenotype is, at least by exclusion, suggestive of T‐cells and as such confirms earlier studies using T‐cell enzyme markers.