Proffered papers 9.30–10.00 Monday 15 September 2003

Both the original Bethesda system and the current UK classifications of cervical cytology have proved robust but each has a major weakness in the area of abnormalities of uncertain significance. Cytologists recognize that sometimes it is simply impossible to differentiate between reactive and dyskaryotic material. For this reason, the Australian version of the Bethesda system introduced a new category of 'high grade inconclusive' with a recommendation for referral to colposcopy. Approximately 60% of such cases are found to have high grade lesions at colposcopy (Schoolland M, Sterrett G, Knowles S et al .). The present UK system even with the proposed changes requires of the pathologist, a decision as to whether such cases are probably high grade (=a report of moderate dyskaryosis) or not (= a report of borderline). This continues to ignore the fact that sometimes you just cannot tell, even on review. We have taken a consecutive series of 50 referral smears, reported as moderate dyskaryosis, where the histological outcome (by loop cone) is known. These cases were rescreened and then reviewed blind by a pathologist with extensive experience of the Australian NH & MRC modified Bethesda system. On review, the material was reclassified along NH & MRC lines. The results were compared with the biopsy findings in order to determine whether the category of 'inconclusive' might be of value in the context of the NHSCSP.     

Relationship between ascorbic acid and cell division

Proliferating cells require large amounts of ascorbic acid to reach cell division. The decrease in ascorbic acid caused by adding lycorine, an inhibitor of ascorbic acid biosynthesis, induces profound inhibition of cell division: the cell cycle is arrested in G1 and G2 phase, more than 90% of the cells being accumulated in G1 after some time. The effect of lycorine on mitotic index (MI) has been reversed by increasing experimentally the concentration of ascorbic acid in tissues. Ascorbic acid control on cell division is found to be specific, since isoascorbic acid is wholly ineffective. It is suggested that the principal role of ascorbic acid in the cell cycle may be related to its action in controlling the synthesis of hydroxyproline-containing proteins, which can be essential requirements for development of G1 and G2.     

Decreased interleukin-2 responsiveness in leukocytes from Trypanosoma brucei-infected mice

Immunosuppression with respect to those inducible processes which regulate lymphocyte mitogenesis was examined in experimental trypanosomiasis. Splenic leukocytes from Trypanosoma brucei-infected mice showed a decreased proliferative response to the T-cell mitogen concanavalin A. Activated cells secreted normal levels of the endogenous T-cell proliferative signal interleukin-2 (IL-2) and expressed high-affinity IL-2 receptors. However, the ability of activated cells to proliferate in response to exogenous IL-2 was inhibited. These results indicate an impairment of processes which occur after IL-2-receptor binding during lymphocyte mitogenesis. Furthermore, these data indicate that expression of high-affinity IL-2 receptors does not necessarily correlate with an ability to respond to IL-2.