Plasma carnitine and cholesterol levels in monkeys and pigeons: species/breed differences and the influence of gender and diet.

1. Total plasma carnitine and cholesterol were studied in two breeds of pigeon and four species of sub-human primates. 2. The levels of plasma carnitine and cholesterol differed within species and between species and were influenced by diet and gender. 3. In the animals studied, pigeons had the highest levels of plasma carnitine (greater than 120 nM/ml) and Squirrel monkeys (Saimiri sciureus) had the lowest levels (ca. 10 nM/ml). 4. Linear regression analysis of plasma carnitine and cholesterol in the monkeys and pigeons indicated no strong correlation between these parameters.     

Local xenogeneic graft-vs-host reaction: a practical assessment of T cell function among cancer patients.

The local xenogeneic graft-vs-host reaction (XGVHR) was used as a practical bioassay to assess T lymphocyte function and immunocompetence among cancer patients. Positive XGVHR was found in 99.5% of normal donors, 70% of cancer patients with early stage disease, and 30% of cancer patients with metastatic disease (p less than 0.001). A minimum of 4.5 x 10(6) immunocompetent T lymphocytes are necessary in order to elicit a positive XGVHR. Negative reactions among cancer patients are characterized by the lack of edema fluid accumulation and the appearance of the most basophils at the test site. This suggests that insufficient amounts of lymphokines are being released by the incompetent T lymphocytes, whereas the host is capable of mounting a rejection reaction as evidenced by the appearance of the basophils. Preliminary evidence suggests that the immunologic defect detected by the XGVHR cannot be corrected by monocyte depletion. The identification of putative suppressor T cell subsets may bear immunotherapeutic implications in the future.     

Immune restoration and/or augmentation of local xenogeneic graft versus host reaction by Cimetidine in vitro

The immunorestorative effect of Cimetidine in vitro on the T cell-induced local GVH reaction in vivo was studied in 43 cancer patients and 43 normal healthy donors. Both low dose (10(-5) M) and high dose (10(-4) M) Cimetidine induced significant, albeit partial, immune restoration among GVHR-negative cancer patients (p less than 0.05, p less than 0.01, respectively) with the high dose being significantly more effective (p less than 0.05). In contrast, similar Cimetidine doses induced only moderate augmentation (p greater than 0.05) among GVHR-positive cancer patients and a marginal one among normal healthy donors. In the latter 2 groups, Cimetidine was found to be occasionally detrimental in that it induced a conversion from a positive to a negative GVH reaction. These results support the concept of anti-suppressor cell activity ascribed to Cimetidine. However, the possibility of a detrimental effect should be born in mind in planning future clinical trials. We propose that the use of Cimetidine be limited to cancer patients with documented increase in suppressor cell activity associated with defective T cell function under close serial monitoring.