Kathleen L. Tarr

Modulation of Cellular Immunity in Medical Students

This study assessed the psychosocial modulation of cellular immunity in 34 medical-student volunteers. The first blood sample was obtained 1 month before examinations, and the second on the day of examinations. There were significant declines in the percentage of helper/inducer T- lymphocytes, in the helper/inducer-suppressor/cytotoxic-cell ratio, and in natural killer-cell activity in the blood samples obtained on the day of examinations. Half of the subjects were randomly assigned to a relaxation group which met between sample points; the frequency of relaxation practice was a significant predictor of the percentages of helper/inducer cells in the examination sample. Three biochemical nutritional assays (albumin, transferrin, and total iron-binding protein) were within normal limits on both samples. Data from the Brief Symptom Inventory showed significantly increased global self-rated distress associated with examinations in the no-intervention group, compared to nonsignificant change in the relaxation group. Clinical and theoretical implications are discussed.

Stress-related impairments in cellular immunity

The percentages of total T-lymphocytes (OKT-3+), helper T-cells (OKT-4+), and suppressor T-cells (OKT-8+) were significantly lower in blood samples obtained from 40 medical students during examinations, compared to baseline values obtained 6 weeks earlier. In addition, the response of T-lymphocytes to stimulation by phytohemagglutinin and concanavilin A was also significantly lower during examinations, compared to baseline. Self-report data documented significantly greater distress associated with examinations. The data have implications for immunosuppressive disorders and stress-related illnesses.

Effects of stress on methyltransferase synthesis: an important DNA repair enzyme.

The enhancement of tumor development following acute stress has been demonstrated in some animal studies. This study was designed to explore mechanisms that would account in part for the relationship between stress and tumor development at the level of DNA repair, using a rat model. Forty-four rats were given the carcinogen dimethylnitrosamine in their drinking water, and half were randomly assigned to a rotational stress condition. The levels of methyltransferase, a DNA repair enzyme induced in response to carcinogen damage, were significantly lower in spleens from the stressed animals. These data suggest that stress may impair DNA repair.

Superinfecting Activity of the B95–8 Isolate of Epstein-Barr Virus

The B95–8 isolate of Epstein-Barr virus (EBV) has been characterized as a transforming strain (1). In contrast, the P3HR-1 (HR-1) isolate has been shown to superinfect latently infected cells such as Raji and NC-37 cells (2), Differences in the activities of these strains of EBV have been thought to be, at least in part, due to specific characteristic deletions in the viral genomes (3). A third isolate of EBV, derived from an epithelial (Ad-AH)/epithelial (NPC tumor) hybrid designated NPC-KT has been shown to have both transforming and lytic biological properties (4,5). Recent work in our laboratory has shown that, by using 100x concentrates of culture supernatants, superinfecting activity can be demonstrated for the B95–8 isolate of EBV.

The Transforming Activity of a Nasopharyngeal Carcinoma-Derived Epstein-Barr Virus Isolate

The Epstein-Barr virus (EBV) is very efficient in growth transforming human and certain non-human B-lymphocytes into transformed lymphoblastoid cell lines (LCL’s). The LCL’s have the ability to grow in medium containing low serum concentrations, the ability to grow indefinitely, and the ability to grow in soft agar, all changes in biological properties associated with EBV transformation (1). Lymphoblastoid cell lines obtained from Burkitt’s lymphoma (BL) tumors exhibit all of the above properties, plus the ability to induce tumors in nude mice (2). This property was though to be an important difference between laboratory derived LCL’s and tumor derived cell lines (1), however a recent study challenges the universality of this concept. (3)