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We have been able to demonstrate that glutaraldehyde fixation of tumor cells or tumor cell membrane fragments protect syngeneic mice against the subsequent challenge with viable cells. To date we have not been able to detect any antibody against the tumor cells in animals so immunized. The specificity of the response is not complete, although a major component of the protective effect of glutaraldehyde-treated tumor cells is immunologically specific.

Friend leukemia virus (FLV) leukemogenesis was prevented by treatment of the virus with Concanavalin A (Con A). Mice infected with the lectin-treated virus, however, showed evidence of a dormant infection since infectious virus could be recovered for as long as 100 days. Humoral immune responses to sheep erythrocytes (SRBC), a thymus-dependent antigen, and to E. coli lipopolysaccharide (LPS), a thymus-independent antigen, were depressed (approximately 80-90%) in mice given the Con A-treated FLV. Cell transfer studies indicated that the impaired responsiveness to SRBC was related to a defect in B-lymphocyte function, similar to the impairment in mice infected with untreated FLV. The mitogenic response of splenocytes from Con A-FLV mice to E. coli LPS was also depressed as was the ability of Ig-bearing spleen cells to redistribute these immunoglobulin receptors into polar caps. The impaired immune responsiveness in the Con A-FLV infected mice appeared associated with the persistent virus infection and not to neoplastic transformation generally associated with leukemogenic process.

A two-plate stripline is used to determine wide-band radio-frequency (285-4000 MHz) absorption characteristics of 96-390-g rats and brain-phantom prolate spheroidal bodies. The results compare well to those for free space irradiation. At resonance, for E along the long dimension (â), a power deposition nine times higher than that for the H parallel â orientation is observed. For rats in the k parallel â configuration, the frequencies of peak absorption and the maximum absorption at these values demonstrate W-1/3 and W 2/3 dependencies, respectively, upon the weight W of the animal. This finding implies that whole animal absorption is a size- and shape-dependent phenomenon.

TA3-HA nonspecific tumors growing in ascites form shed their membrane components into the ascites fluid. This product can induce tumor growth enhancement if given together with or after i.p. tumor inoculation in relatively large quantities, but if given i.m. in small quantities, several days before tumor challenge, the mice show an elevated resistance to the tumor. The strictly strain-specific TA3-St line does not release such membrane components into the ascites fluid. It has also been found that the TA3-HA cells have a larger membrane fluidity than the TA3-St cells, as measured by membrane microviscosity, using the Shinitzki procedure. Isolation and gross chemical analysis of the TA3-Ha ascites fluid component was carried out. Results, so far, indicate that the active site of this product is probably carbohydrate in nature. The possible mode of action of such component in tumor growth enhancement is most probably by overwhelming and neutralizing immunocytes capable of recognition and eventually cytotoxic action.

A fraction with lymphokine properties was isolated from supernatant medium of the continuous cultured human lymphoblast cell line, 1788. Culture medium containing 2% human serum was used for cell growth in order to minimize antigenicity of supernatant fractions isolated from the medium. The culture medium was passed through an Amicon XM-100 membrane, concentrated over a PM-10 membrane, lyophilized, and reconstituted to a final concentration of approximately 40:1. Studies in vivo and in vitro showed that the active fraction contained skin reactive factor (when injected intradermally into guinea pigs and humans), lymphotoxin, migration inhibition factor, chemotactic factor, and macrophage activation factor. This same preparation, when injected intralesionally into cutaneous tumors, induced an inflammatory reaction followed by tumor regression. The fraction confined between membranes of pore size 10,000-100,000 daltons was active in promoting tumor regression, while the fraction less than 10,000 daltons was inactive. Patients with skin lesions from metastatic carcinoma of the breast and other malignancies were studied, and 16 out of 30 treated lesions were judged to have undergone either complete or greater than 50% regression. Of these, 8 were biopsied before and after lymphokine injection, and 6 out of 9 were negative for tumor cells. Additional studies in vitro with material fractionated on Sephadex G-200 indicated that the macrophage-activating component binds to alpha-2 macroglobulin in the culture medium.

Mice were actively immunized against Friend leukemia virus tumorigenesis by vaccination with cell-free homogenates derived from infected splenocytes emulsified in Freund's adjuvant. Adoptive immunity was also achieved by transferring splenocytes from actively immunized donor animals intravenously into syngeneic recipient animals challenged with the virus. Furthermore, RNA-rich extracts derived from spleens of actively immunized donor animals were capable of transferring immunity to FLV leukemia when injected into recipient animals challenged with the virus. The "immune RNA," when incubated with normal splenocytes in vitro, followed by washing, resulted in a cell population that also induced adoptive immunity after transfer to normal animals challenged with virus either before, simultaneously with, or after injection of the treated splenocytes. RNase, but not DNase or other enzymes, inactivated the biologie activity of the protective RNA from immune donors. In addition, isogeneic mouse serum that contained neutralizing antibody to FLV also inhibited the protective effect of the specific RNA; sera from control mice immunized with unrelated antigens failed to neutralize the specific RNA. These results indicate that an RNA extract that contains a virus-associated or -induced antigen is formed in the spleens of actively immunized animals and possesses the ability to either directly induce protective immunity in recipient animals challenged with virus or, indirectly, to convert normal splenocytes in vitro to adoptively confer immunity to similar recipients. Further investigations concerning the mechanism by which such immunogenic RNA functions in vivo and in vitro, as well as the physicochemical nature of the RNA complex, especially that portion associated with the tumor virus-associated antigen, are needed.

In vitro incubation of isolated X. laevis oocytes with progesterone induces the specific labeling of proteins during maturation. They are detected as several discrete peaks with a double-labeling technique that involves the injection of [3H] leucine into hormone-treated and [14C] leucine into control cells. The peaks are separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Identical proteins are obtained with two other steroids that provoke maturation and with p-chloromercuribenzoate. The same progesterone-induced proteins are observed even if oocytes have been treated with actinomycin D or ethidium bromide or have been enucleated. Cycloheximide suppresses the labeling of proteins that are induced by progesterone, if administered either at the time of radioactive amino acid exposure or after prelabeling the oocytes to determine whether the hormone-induced peaks are due to compartmental changes of the proteins. A cytoplasmic fraction, obtained from maturing oocytes before GVBD, promotes maturation when injected into resting oocytes and therefore contains an MPF. After this injection, GVBD occurs earlier than during incubation with progesterone and is accompanied by the formation of the same proteins and of MPF, both suppressed by cycloheximide. The possibility that MPF is an induced protein is then discussed. It has been also found that there is a decrease in membrane permeability, as evidenced by decreased leucine uptake into proteins of oocytes incubated in radioactive amino acids and exposed to progesterone. The same decrease occurs after injection of MPF-containing cytoplasm into oocytes.