Discrimination between normal and malignant hepatocytes in man by the monoclonal antibody RL23/36: comparison with the Ca1 and 791T/36 monoclonal antibodies.

The monoclonal antibody RL23/36 has been shown to discriminate normal from malignant hepatocytes in man. In frozen sections of liver tissue from 25 Thai patients without hepatocellular carcinomas, the antibody reacted strongly and preferentially with hepatocytes. Reactivity with 7 hepatocellular carcinomas was invariably abnormal, being totally absent in 5 and partially lost in 2. This discrimination was superior to that achieved with Ca1 and 791T/36 monoclonal antibodies. In 2 cases of hepatocellular carcinoma, binding of RL23/36 to associated apparently non-malignant hepatocytes was abnormal, being absent in one and partially lost in the other. These data show that RL23/36 detects an antigenic determinant which is lost during malignant transformation of human hepatocytes, sometimes before the development of frank malignancy.

Time trends in the analysis of incidence rate of leprosy among household contacts.

Analysis of time trends in the Incidence Rates among 9.598 household contacts of 1,614 primary cases of leprosy, showed that the incidence rates (IR) remained high even 10 years after treatment was started in the Primary Case. The IR during the 1st year of follow-up was 3.8 per 1000 person years of risk (PYR) and the IR was 3 per 1000 PYR after 10 or more years of follow-up. The significance of these findings in relationship to the Epidemiology of leprosy among household contacts in an endemic area for leprosy is discussed.

Incidence rates of leprosy among household contacts of "primary cases".

The data consisted of information from 1,564 "Primary cases" of leprosy of all classification and 9,162 of their household contacts. Household contacts of Indeterminate (Ind), Borderline (BL) and Lepromatous (LL), "Primary case" (PC) had an incidence rate (IR) of 5 per 1000 person years of risk (PYR). Household contacts of Tuberculoid (TT) and borderline tuberculoid (BT) patients had an IR of 3.2 and 3.8 per 1000 PYR respectively. Compared with an incidence rate of leprosy of 1.6 per 1000 PYR among individuals not exposed to leprosy in the same area, household contacts of Non-lepromatous patients had a relative risk of twice as high and contacts of lepromatous and borderline lepromatous patients a relative risk of 3 times as high. The incidence rate was higher among household contacts of bacteriologically positive patients, among contacts closely related and in households with multiple cases. The peak age specific incidence rate among household contacts was between the ages 5-9 years of age. The significance of these findings are discussed.