Pulse interleukin-2 with famotidine induces CD56+ lymphocytes in the peripheral blood of patients with metastatic melanoma or kidney cancer.

Increased lymphokine-activated killer (LAK) cell numbers and cytotoxicity against tumor cell lines have been seen in patients receiving high-dose continuous and bolus infusion interleukin-2 (IL-2) regimens. LAK are CD56 positive on flow cytometry. Daily intravenous doses of IL-2 of 18-21.6 MIU/m(2) over 15-30 minutes ("pulses") have been developed to attempt to lessen the toxicity of this therapy. It has been previously shown that the patients with metastatic melanoma or kidney cancer may be treated safely with pulse IL-2 daily for 5 days preceded by intravenous famotidine. Cycles were repeated every 21 days. Because LAK numbers have not been previously described with this regimen, the present study has examined CD56 numbers via peripheral blood flow cytometry in 11 patients with samples scheduled at baseline, after two cycles, and after four cycles. Eight (8) patients had melanoma and 3 had kidney cancer. Median CD56 counts after two cycles was significantly higher than baseline (p = 0.001). Similarly, CD56 counts at 2 months later were also greater than baseline (p = 0.009). There was no difference between median values after two cycles versus after four cycles. Patients who were clinical responders had a median CD56 count of 650 after two cycles when compared with nonresponders who had a median CD56 count of 290 (p = 0.005). CD56 counts are significantly elevated in patients treated with pulse IL-2 with famotidine and clinical responders have significantly higher CD56 than nonresponders.

A novel method to display [gal alpha1, 3 gal] antigens on human leukemic cells for preparation of anti-leukemia vaccines.

BACKGROUND: Expression of the immunostimulatory xenoantigen alphaGal on malignant cells is being investigated as a means to formulate anticancer vaccines. Expression methods have been limited to gene transfer using viral vectors and enzymatic manipulation. We report here a novel method using polyethylene glycol (PEG) to induce plasma membrane fusion between malignant human hematological cells and alphaGal(+) porcine blood cells (PBC) in order to display alphaGal antigens on human cells. MATERIALS AND METHODS: Freshly isolated white blood cells (WBC) were obtained from patients with malignant hematological disease and combined with diluted PBC. Cell mixtures were labeled with human CD mAbs, followed by IB4 lectin or M86 mAb to detect alphaGal antigens and then co-incubated with PEG. Back-gated, dual-color flow cytometry was used to detect alphaGal on human cells. RESULTS: alphaGal antigens were detected on sizeable numbers of human WBC (approximately 45%) after incubation with PEG. Antigen expression was profuse as assessed by the strong fluorescent intensity demonstrated by IB4-FITC and M86 labeling. Human cells combined with PBC without PEG were not reactive with IB4-FITC or M86. CONCLUSION: Our method provides an effective, highly reproducible means to efficiently express alphaGal antigens on cells obtained from patients with a spectrum of hematological malignancies. This method can provide a simple, safe alternative to viral-mediated gene transfer or enzymatic alteration to express alphaGal antigens on human tumor cells. By virtue of its simplicity, our technique presents a novel approach to the preparation of polyvalent autologous or syngeneic anticancer vaccines.