Suramin, a polysulphonated naphthylurea proven to be an effective anticancer agent against selected tumours, and alpha 2A-interferon (alpha 2A-IFN) were investigated for their combined effects on HCT-8, HCT-15, CL-D, SW-480 and SW-620 human colorectal adenocarcinoma cell lines. All lines were sensitive to clinically achievable concentrations of suramin in a dose-dependent manner, while alpha 2A-IFN alone induced only a modest reduction of cell growth. Concomitant treatment with suramin and alpha 2A-IFN resulted in a synergistic inhibition of cell viability in each cell line at all doses tested. However, when suramin and alpha 2A-IFN were administered sequentially, inhibition of cell viability was clearly dependent on the timing of treatment schedule, with maximum effect obtained when alpha 2A-IFN was administered prior to suramin. In contrast, pretreatment with suramin was markedly inferior to the former one. In conclusion, suramin and alpha 2A-IFN exert a synergistic effect on human colorectal cell proliferation in vitro at clinically achievable concentrations. This observation may have clinical relevance although the mechanisms of interaction remain to be elucidated.

The saliva of cats infected with feline immunodeficiency virus was examined for total immunoglobulin content and antiviral antibodies. Seropositive cats showed an increase in salivary immunoglobulin G levels, which was only partly attributable to the enhanced prevalence of oral inflammatory lesions, compared with the levels in seronegative cats. Immunoglobulin G, but not immunoglobulin M, levels in serum were also increased. Salivary antibodies were determined by indirect immunofluorescence and Western blot (immunoblot) analysis. All but 1 of the 16 seropositive cats examined were positive, while all 16 control cats were negative. The presence of oral lesions was not a prerequisite for antibody detection in saliva. It was concluded that salivary antibody might be usefully exploited for diagnostic and epidemiologic purposes.

Thiobenzamide (TB) is a thiono-containing compound endowed with liver-damaging properties and promoting ability on liver carcinogenesis. When administered in a single dose to normal as well as to adrenalectomized rats, this compound induced a striking thymus cortex involution without relevant effects on the morphological features of other lymphoid organs such as spleen and lymph nodes. The proximal TB metabolite TB-S-oxide (TBSO) shared these effects with the parent compound, whereas the terminal metabolite benzamide (BA) was ineffective. The effect of TB on thymus was found to be dose- and age-dependent. Furthermore, acute TB treatment 12h before priming with the T-dependent antigen sheep erythrocytes impaired the secondary antibody response. In addition, TB administration affected not only cell-mediated immunity (as evidenced by a decreased delayed hypersensitivity response) but also mitogen-induced proliferation of blood lymphocytes. On the contrary, the chemotactic response of polymorphonuclear leukocytes obtained from TB-treated rats was unchanged.