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Enzyme activities were studied in peripheral blood lymphocytes from patients infected with, or at risk for, infection with human immunodeficiency virus (HIV). No significant differences were observed in the HIV-infected and HIV-seronegative high-risk patients with regard to enzyme activities of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) and purine nucleoside phosphorylase (EC 2.4.2.1) in peripheral blood. Adenosine deaminase (EC 3.5.4.4) was significantly (P less than 0.02) depressed in asymptomatic HIV-seropositive patients and HIV-seronegative patients at high risk of HIV infection as compared with a healthy HIV-seronegative population. Adenosine kinase (AK, EC 2.7.1.20) was significantly increased in the asymptomatic seropositive (P less than 0.02) and also in the HIV-seronegative high-risk groups (P = 0.01) compared with the normal controls. AK activity was significantly lower in subjects with AIDS than in the asymptomatic (P less than 0.002) and high-risk groups (P less than 0.01). Taken together, these results indicate that adenosine deaminase and AK activities are influenced by the health of the patient, and that measurement of AK activity may prove useful in monitoring the clinical progress of patients with HIV infection.

A prospective study on 100 homosexual male volunteers was designed to examine immunological function in relation to sexual activity and infection with the human T cell lymphotropic virus Type III (HTLV-III). Complete data were available for 71 men. In a comparison with 100 age-matched heterosexual men, the study group of 100 men had a significantly higher mean serum IgG level (12.1 +/- SD 2.7 g/l vs. 10.9 +/- 2.4 g/l, p less than 0.01) and a significantly lower mean number of CD4 (T4) cells (845 +/- 310 X 10(-6)/l vs. 1128 +/- 375; p less than 0.01). For the study group, seropositivity for anti-HTLV-III was present initially in 22 per cent and was associated with a higher mean level of serum IgG and lower mean number of CD4 cells. Among seropositive homosexual men a low CD4/8 ratio was attributable to low numbers of CD4 cells in those without lymphadenopathy and to high numbers of CD8 cells in those with lymphadenopathy. For the seronegative homosexual men, a low CD4/8 ratio as a result of an increased CD8 cell count was present in 12 of 60, and was associated with numerous sexual partners and semen culture positive for cytomegalovirus. In two seropositive subjects a low CD4/8 ratio due to a decrease in the CD4 cell count was predictive of the development of AIDS by some two years. For the 71 men with complete data over two years, indices of cell-mediated immunity, including mean counts of CD4 cells, the CD4/8 ratio, and score for recall of cutaneous delayed type hypersensitivity increased during the first year but not during the second year in both seropositive and seronegative subjects. These increases occurred in association with changes in sexual practices and activity, but could not be attributed to any one particular factor.

A survey was undertaken of homosexual and bisexual men in Brisbane to establish whether knowledge of their human immunodeficiency virus (HIV)-antibody status had influenced any sexual behaviour that was likely to spread HIV type 1 (HIV-1). Of the 318 respondents, 123 respondents knew their HIV serological status, and 13 of these were HIV seropositive. Of the 195 respondents who previously had not been tested, 10 individuals proved to be HIV seropositive. Eighty-two per cent of subjects stated that they had reduced their sexual activity because of their awareness of the acquired immunodeficiency syndrome (AIDS); this reduction was equally common among those who had or had not previously had their HIV serological status checked. Anal intercourse was practised most frequently by those subjects who were HIV seropositive and were not aware of it; nevertheless, unprotected anal intercourse was common among subjects who knew their HIV serological status, including those who knew that they were HIV seropositive. Eighty-nine of 208 subjects who were practising anal intercourse had never used a condom. Usage of a condom was marginally more common among those subjects who previously had been tested for the presence of HIV antibodies (P = 0.06), and this was particularly so for those subjects who knew that they were HIV seropositive (P less than 0.01). Condom usage was no more common among those subjects who knew that they were HIV seronegative, when compared with those subjects who did not know their status. These data show that knowledge of a negative HIV-antibody test-result has no substantial association with safer sexual behaviour and suggest that whereas targeted information programmes have had some impact on behaviour in high-risk groups in Brisbane, by the end of July 1986, these programmes had not yet resulted in safer sexual practices by the majority of homosexual and bisexual men.

Twelve asymptomatic HIV seropositive subjects ages 21 to 40 years were examined for serologic evidence of cerebral HIV infection, for cerebral structural abnormalities, and for neuropsychologic evidence of cerebral dysfunction using standard methods. Eleven of the 12 had antibody to HIV in the cerebrospinal fluid (CSF). Nine subjects had oligoclonal immunoglobulins in the CSF, of whom five had some for which there were no corresponding serum oligoclonal immunoglobulins ('unique' oligoclonal immunoglobulins). Intracerebral synthesis of HIV specific antibodies was demonstrated for four subjects. Significant deficits of memory and frontal lobe function were found in five of the 12 subjects. Subjects who had oligoclonal immunoglobulins unique to the CSF all had significant neuropsychological abnormalities. No structural cerebral abnormalities were demonstrated using CT scanning for any subject tested. These results support other evidence that HIV is neurotropic and capable of directly inducing brain damage even in immunologically normal subjects. Tests of memory and frontal lobe function are frequently abnormal in patients with early HIV infection, and identify as abnormal a similar group of patients to immunological or biochemical tests which might indicate cerebral HIV infection.

Cells from the anorectal mucosa of 61 homosexual men were examined microscopically for evidence of papillomavirus infection and dysplastic changes. There was cytological evidence of dysplasia with concomitant features of human papillomavirus (HPV) infection on at least one occasion in 24 men and of papillomavirus infection without dysplasia on at least one occasion in a further 26: dysplasia was present for over one year in 9 of 14 men who were re-examined. Dysplasia was associated with a history of anal warts, frequent receptive anal intercourse, presence of serum antibody to human immunodeficiency virus (HIV), and immune dysfunction as judged by a low CD4/CD8 ratio, but not with the lifetime number of sexual partners. The association of longlasting dysplasia with anti-HIV was independent of the association with immune dysfunction. Thus infection of anorectal mucosal cells with papillomavirus seems to be frequent among homosexual men and may predispose to dysplasia.