Israel Siegel

Suppression of T-Lymphocyte Rosettes by Rifampin: Studies in Normals and Patients with Tuberculosis

Studies of circulating T- and B-lymphocyte rosettes were done in 20 healthy controls and 29 patients with pulmonary tuberculosis, including 18 receiving rifampin chemotherapy. Eight of the 18 patients in the rifampin group (44%) had significant suppression of their T-cell rosettes as compared with patients with tuberculosis not receiving rifampin (P less than 0.005). Seven of the eight patients with suppressed T-cell rosettes had received the drug for longer than 6 weeks. No significant difference was observed in circulating T- and B-lymphocyte rosettes between healthy controls and patients not receiving rifampin. Administration of this drug to two healthy subjects in a dosage of 600 mg daily for 28 days was associated with suppression of T-lymphocyte rosettes. The maximum decreases of 40% and 37% were observed at 14 and 21 days respectively, with return to base-line values within 2 weeks of discontinuation of drug therapy; this indicates complete reversibility. Long-term sequential studies will be required to determine whether T-cell suppression after prolonged therapy with rifampin is also reversible or associated with any harmful sequels.

Effects of short-term dietary restriction on survival of mammary ascites tumor-bearing rats.

We studied the effects of short-term dietary restriction on the survival of 3-4-month-old tumor-free and tumor-bearing Fisher rats. The diet-restricted food regimen consisted of alternate day ad libitum feeding followed by alternate day fasting. Diet-unrestricted control rats were fed ad libitum daily. Six tumor-free rats on the diet-restricted regimen compensated for the dietary restriction by an increase in food consumption during the alternate feeding days, and lost an average of only 2-3% of their weight in 13 days. Six tumor-free rats on a daily ad libitum feeding regimen gained an average of 6.8% in 15 days. The above dietary-restricted regimen was initiated 1 week before 24 rats were inoculated intraperitoneally with 15 million Mat 13762 ascites tumor cells. Sixteen of 24 (66.7%) diet-restricted tumor-bearing hosts and 5/24 (20.8%) diet-unrestricted tumor-bearing hosts survived at 9 days after tumor inoculation (p less than 0.005). Twelve of 24 (50%) diet-restricted tumor-bearing hosts, and 3 of 24 (12.5%) diet-unrestricted tumor-bearing hosts, survived at 10 days after tumor inoculation (p less than 0.025). Thus, the survival of tumor-bearing rats was enhanced by short-term relatively mild dietary restrictions. We suggest that relatively mild dietary restrictions should be included in clinical trials designed to inhibit cancer growth and enhance the survival of human cancer patients.

Fc- and complement-receptor rosette-forming cell ratios in human tonsils and peripheral blood.

Lymphocytes were investigated for both Fc- and complement-rosette-forming cell activities. At least three subpopulations differing in the relative activities of the Fc and complement receptors have been disclosed. In human tonsils a subpopulation of B lymphocytes had a higher complement-receptor activity than Fc-receptor activity. In contrast, the peripheral cells from a patient with a lymphoma and another with an undiagnosed lymphocytic disease contained a population of B lymphocytes with higher Fc-receptor than complement- receptor activity. In three patients with chronic lymphocytic leukemia, B lymphocytes contained both Fc- and complement-receptor activities. No differences between complement- and Fc-receptor activities were evident in normal human peripheral blood. Fc-receptor, but not complement-receptor activity was inhibited by 2% gamma-globulin, or 8 X 10(3) M iodoacetate. EDTA at 1.7 X 19(-2) M concentration has no effect upon Fc- or complement-rosette-forming cells. The activity of both receptors was diminished at 4 degrees C.

Inhibition of sperm motility and agglutination of sperm cells by free fatty acids in whole semen**Supported by the Foundation for Reproductive Medicine, Inc., Chicago, Illinois.

The effects of a serial dilution of linoleic acid on human spermatozoa in whole semen was tested on 21 semen samples obtained from 11 normal volunteers. The minimal concentration of linoleic acid required to stop the movement of at least 75% of the moving sperm ranged from 1 to greater than 100 mg/dl. Fifteen of 21 (71%) of the semen samples were inhibited by added free fatty acids (FFA) concentrations that were less than or close to the physiologic concentration ranges of FFA in blood plasma (1 to 30 mg/dl). The immobilized sperm often formed aggregates similar to those formed by the action of autoantibodies against sperm cells. Preliminary studies conducted on a variety of other FFA have indicated that oleic acid (18/1) was less toxic than linoleic acid (18/2) and that linolenic acid (18/3) was more toxic than linoleic acid. The saturated FFA palmitic acid (16/0) and stearic acid (18/0) at concentrations up to 100 mg/dl showed little or no toxicity to sperm cells. It is suggested that FFA toxicity be included among physiologic factors that affect the motility and spontaneous aggregation of sperm cells.