Yokota S, Hara H, Luo Y, Seon B K
Department of Molecular Immunology, Roswell Park Memorial Institute, Buffalo, New York 14263.
Cancer Res. 1990 Jan 1;50(1):32-7.
In the present study, immunotoxins (ITs) containing ricin A chain (RA) and anti-human T leukemia monoclonal antibodies SN1 and SN2 were used with or without alpha-interferon (IFN) and/or daunorubicin (DNR) for in vivo tumor suppression. SN1 and SN2 are directed toward two unique human T-leukemia-associated cell surface antigens, TALLA and GP37, respectively. As the tumor model, we used nude mice bearing ascitic tumors of Ichikawa, a human T acute lymphoblastic leukemia cell line. In initial studies, we investigated the effect of the IT injection schedule on the efficacy of ITs in the in vivo suppression of the ascitic tumors. Four doses of 20 micrograms each of SN1-RA and SN2-RA completely suppress the tumor growth in 100% of the treated mice when the IT treatment is initiated either 1 or 2 days after tumor inoculation of 1.6 x 10(7) Ichikawa cells into the mice. Subsequently, we investigated the potentiating effects of IFN and DNR on the in vivo antitumor activity of ITs. To this end, we chose to initiate the treatment 4 days after the tumor inoculation when IT treatment alone is only partially effective. ITs (10 micrograms each of SN1-RA and SN2-RA) plus IFN (2 x 10(5) IU) or ITs plus IFN plus DNR (5 micrograms) completely suppress tumor growth in 100% of the treated mice while similar treatment with any one of the three agents is only partially effective. Similar treatment with ITs plus DNR or IFN plus DNR results in complete suppression of tumor growth in 80% of the treated mice. These results were reproducible in a repeated experiment. To gain information about the mechanisms involving the IFN potentiation of IT activity, we carried out several experiments. The cell surface expression of TALLA and GP37 was slightly augmented by the in vitro incubation of Ichikawa cells with IFN as measured by fluorescence-activated cell sorter analysis. The degree of the increase in either TALLA or GP37 was significantly smaller than that of HLA class I antigens in the same experiment. In in vitro experiments, IFN did not show any significant cytotoxic activity against Ichikawa cells or augment the cytotoxic activity of ITs against Ichikawa cells. On the other hand, injections of IFN into nude mice augmented activity of macrophages and NK cells; however, Ichikawa leukemia cells were rather resistant to the NK cell lysis.(ABSTRACT TRUNCATED AT 400 WORDS)
在本研究中，含有蓖麻毒素A链（RA）以及抗人T白血病单克隆抗体SN1和SN2的免疫毒素（ITs），在有或没有α干扰素（IFN）和/或柔红霉素（DNR）的情况下用于体内肿瘤抑制。SN1和SN2分别针对两种独特的与人类T白血病相关的细胞表面抗原，即TALLA和GP37。作为肿瘤模型，我们使用了携带市川人T急性淋巴细胞白血病细胞系腹水瘤的裸鼠。在初步研究中，我们研究了IT注射方案对ITs体内抑制腹水瘤疗效的影响。当在将1.6×10⁷个市川细胞接种到小鼠体内后1天或2天开始IT治疗时，每只小鼠注射4剂各20微克的SN1 - RA和SN2 - RA可使100%的受试小鼠的肿瘤生长完全受到抑制。随后，我们研究了IFN和DNR对ITs体内抗肿瘤活性的增强作用。为此，我们选择在肿瘤接种后4天开始治疗，此时单独的IT治疗仅部分有效。ITs（各10微克的SN1 - RA和SN2 - RA）加IFN（2×10⁵国际单位）或ITs加IFN加DNR（5微克）可使100%的受试小鼠的肿瘤生长完全受到抑制，而单独使用这三种药物中的任何一种进行类似治疗仅部分有效。ITs加DNR或IFN加DNR的类似治疗可使80%的受试小鼠的肿瘤生长完全受到抑制。这些结果在重复实验中是可重现的。为了了解涉及IFN增强IT活性的机制，我们进行了多项实验。通过荧光激活细胞分选分析测量，市川细胞与IFN体外孵育后，TALLA和GP37的细胞表面表达略有增加。在同一实验中，TALLA或GP37的增加程度明显小于HLA I类抗原的增加程度。在体外实验中，IFN对市川细胞没有显示出任何显著的细胞毒性活性，也没有增强ITs对市川细胞的细胞毒性活性。另一方面，向裸鼠注射IFN可增强巨噬细胞和NK细胞的活性；然而，市川白血病细胞对NK细胞裂解具有相当的抗性。（摘要截断于400字）
