James R. Blakeslee

Effects of steroid hormones in fetal bovine serum on plating and cloning of human cells in vitro

SummaryFetal bovine sera from each of three different commercial sources were tested for their ability to support cloning of human fibroblastoid cells in vitro. Cloning efficiencies varied according to serum source. Serum (10 samples) from company A did not support growth, while sera (10 samples) from companies B and C provided adequate to excellent conditions for cloning and growth. Cells from neonatal foreskin or embryonic lung responded to each serum similarly. Bovine serum albumin type H7 from company C supported cell growth in media without serum.Sera containing 1.0 ng per ml or more of progesterone inhibited growth, whereas sera containing less than 1.0 ng per ml supported cloning and growth. In the low progesterone sera, the concentration of 17-β-estradiol exceeded 100 pg per ml. Growth supporting sera could be made non-supportive by adding 0.1 μg per ml of progesterone. The addition to non-supportive sera of 0.1 μg per ml of 17-β-estradiol or hydrocortisone made these sera supportive of cell growth.Addition of estrogen or hydrocortisone to a culture medium that inhibits growth, with subsequent reversal of the inhibitory effect, implies that these hormones competitively regulate growth of responsive cells in vitro.

Adoptive immunotherapy of feline leukemia virus infection using autologous lymph node lymphocytes.

Adoptive immunotherapy using autologous cells expanded ex vivo from lymph nodes was examined in cats infected with the retrovirus feline leukemia virus (FeLV). Cells were obtained from popliteal lymph nodes from 18 FeLV-antigen-positive cats without complications; a mean of 6.2 x 10(7) cells were obtained. Lymph node cells were cultured with 600 IU/ml interleukin-2 (IL-2) for 7 days. Cells expanded 0.8- to 11-fold (mean, 2.7; median, 2.4); were 80% +/- 8.0% CD3+, 29% +/- 8.1% CD4+, and 41% +/- 7.0% CD8+, and exhibited cytolytic activity against FeLV-transformed FL74 cells. Sixteen cats received a single intravenous infusion of 0.13 to 3.9 x 10(8) cells. Cell infusion was well tolerated; fever developed approximately 1 hour postinfusion. Clinical activity, antiviral activity, or both was observed in 10 cats. Nine cats had clinical responses with improvement in weight, activity, appearance, or a combination of these that began 2 to 4 weeks after cell infusion and that lasted for up to 13 or more months. FeLV antigen became undetectable in 4 cats. These results indicate that adoptive immunotherapy using autologous lymph node cells, activated and expanded ex vivo in short-term cultures with low concentrations of IL-2, can modulate the course of a retroviral infection.

Oncogenic Viruses of Domestic Animals

The objective of this article is to review the relevant oncogenic viruses of small animals. Basic scientific principles that have been discovered by research into feline leukemia and other animal cancer viruses have enhanced our understanding of oncogenesis and have led to practical methods of cancer control and prophylaxis.

Immune recognition of genetically diverse simian T-cell lymphotropic virus type I isolates

SummaryNucleotide sequence analysis of selected regions of the gag, pol, env and pX genes of simian T-cell lymphotropic virus type I (STLV-I) strains indicated that African isolates were more closely related to human T-cell lymphotropic virus type I (HTLV-I) than Asian isolates. Despite these recent comparative studies on nucleotide sequence homology between HTLV-I and STLV-I isolates, only limited information is available regarding the influence of genetic differences on antigen-antibody recognition of distinct STLV-I strains. In this study, we demonstrated that sera from STLV-I-infected yellow baboons (Papio cynocephalus) reacted strongly with env gp62/68 from HTLV-I-infected cell lines MT-2 and C10/MJ. In contrast, sera from Japanese macaques (Macaca fuscata) naturally infected with Asian STLV-I had weak reactivity to env gp62/68 of these prototypic HTLV-I strains. Pst-1 restriction enzyme analysis of proviral DNA indicated that the baboon virus isolates were more closely related to HTLV-I than the Japanese isolates. These results indicate that nucleotide sequence diversity, correlates with variations in proviral restriction enzyme sites and antibody recognition of viral envelope proteins. These differences in immunoreactivity may have important implications for serologic diagnosis, as well as epidemiological and vaccine studies of STLV-I infection.

Zinc effects on nickel dermatitis in the guinea pig

Prevention of NiSO4 induced allergic, contact dermatitis (ACD) using ZnSO4 in drinking water was studied in a guinca pig model Without ZnSO4 intervention, nickel (Ni)‐exposure resulted in significantly higher (p<0.05) stimulation indices (SIs) as compared to non‐exposed controls, using NiSO4 as an allergen in the lymphocyte transformation test (LTT). Oral intake of ZnSO4 at both 250 μg/ml double‐distilled deionized water (DDD) and 500 μg/ml DDD resulted in lower SIs than those of control guinea pigs drinking only DDD: the 250 μg ZnSO4/ml group had significantly lower Sis than (p= 0.025) than controls. There was no significant correlation between intradermal test responses and the SI values of individual guinea pigs exposed to NiSo4 Mean Zinc (Zn) concentrations in skin and in whole blood were not statistically different between the NiSO4 exposed control and Zn supplemented groups, nor between Ni‐sensitive and non‐sensitive animals within groups. The rôle of Zn homeostasis role of the Langerhans cell, effect of Zn supplementation on Ni ACD in other species, and possible blocking effects of other metals should be investigated in future studies.