The extent of immunological privilege of orthotopic corneal grafts in the inbred rat

Corneal grafts are believed to enjoy a degree of "immunological privilege" primarily due to the avascularity of the recipient bed. In this study orthotopic full-thickness corneal grafts were carried out in the inbred rat, using a technique that is a close model of corneal grafting in humans. The survival times of corneal grafts on nonvascularized beds of 28 fully allogeneic strain combinations were determined without the use of immunosuppression. Some combinations were rejected rapidly, e.g. DA (RT1a) into BN (RT1n) with a mean survival time (MST) +/- SD of 7.8 +/- 1.3 days, and some at a moderate rate, e.g. AO (RT1u) into LEW (RT1l) with an MST of 23.1 +/- 10.0 days, whereas in other cases survival was indefinite, e.g. WAG (RT1u) into PVG (RT1c), an MST of greater than 100 days. Orthotopic corneal grafts on nonvascularized beds between DA and AO parents and the F1, followed the basic rules of transplantation genetics. In addition, the rate of graft rejection was significantly faster (P less than 0.001) with corneal grafts from DA into AO placed onto a vascularized compared with a nonvascularized corneal bed (MST of 6.8 +/- 2.4 or 12.1 +/- 4.0 days respectively). The rate of rejection of corneas on a vascularized bed was at a similar rate to that of orthotopic skin or heterotopic auxiliary heart grafts. The results indicate that the fate of a corneal allograft on a nonvascularized bed is dependent upon the particular combination of donor and recipient strain. No consistent association was observed between any donor or recipient RT1 haplotype and survival; this suggests that non-RT1 background genes may play a role in the survival of corneal grafts.     

Drug use and policy in Poland in the 1980s

In this article, the author describes the recent changes in patterns of drug use in Poland in the light of available data. A much higher incidence of use has been seen in the 1980s, and there are indications that this can be accounted for by increased use among young people from the manual working class. Social deprivation may play a part in the etiology of the 1980s "epidemic," and evidence is put forward in support of this view. Both patterns of use and the policies that have been introduced to deal with them are viewed in terms of the political, economic, and social context of post-Solidarity perestroika.     

Protection from pathogenic SIV challenge using multigenic DNA vaccines

To assess DNA immunization as a strategy for protecting against HIV infection in humans, we utilized SIVmne infection of Macaca fascicularis as a vaccine challenge model with moderate pathogenic potential. We compared the efficacy of DNA immunization alone and in combination with subunit protein boosts. All of the structural and regulatory genes of SIVmne clone 8 were cloned into mammalian expression vectors under the control of the CMV IE-1 promoter. Eight M. fascicularis were immunized twice with 3 mg of plasmid DNA divided between two sites; intramuscular and intradermal. Four primed macaques received a further two DNA immunizations at weeks 16-36, while the second group of four were boosted with 250 microg recombinant gp160 plus 250 microg recombinant Gag-Pol particles formulated in MF-59 adjuvant. Half of the controls received four immunizations of vector DNA; half received two vector DNA and two adjuvant immunizations. As expected, humoral immune responses were stronger in the macaques receiving subunit boosts, but responses were sustained in both groups. Significant neutralizing antibody titers to SIVmne were detected in one of the subunit-boosted animals and in none of the DNA-only animals prior to challenge. T-cell proliferative responses to gp160 and to Gag were detected in all immunized animals after three immunizations, and these responses increased after four immunizations. Cytokine profiles in PHA-stimulated PBMC taken on the day of challenge showed trends toward Thl responses in 2/4 macaques in the DNA vaccinated group and in 1/4 of the DNA plus subunit vaccinated macaques; Th2 responses in 3/4 DNA plus subunit-immunized macaques; and Th0 responses in 4/4 controls. In bulk CTL culture, SIV specific lysis was low or undetectable, even after four immunizations. However, stable SIV Gag-Pol- and env-specific T-cell clones (CD3+ CD8+) were isolated after only two DNA immunizations, and Gag-Pol- and Nef-specific CTL lines were isolated on the day of challenge. All animals were challenged at week 38 with SIVmne uncloned stock by the intrarectal route. Based on antibody anamnestic responses (western, ELISA, and neutralizing antibodies) and virus detection methods (co-culture of PBMC and LNMC, nested set PCR- of DNA from PBMC and LNMC, and plasma QC-PCR), there were major differences between the groups in the challenge outcome. Surprisingly, sustained low virus loads were observed only in the DNA group, suggesting that four immunizations with DNA only elicited more effective immune responses than two DNA primes combined with two protein boosts. Multigenic DNA vaccines such as these, bearing all structural and regulatory genes, show significant promise and may be a safe alternative to live-attenuated vaccines.     

Cytogenetic diagnosis using midtrimester fetal blood samples: Application to suspected mosaicism and other diagnostic problems

Cytogenetic studies on fetal blood cells obtained at 18–25 weeks gestation have provided information for decision making in 25 cases identified as being at high risk of having an abnormal fetus. In particular, in the 21 cases studied to consider the possibility of true mosaicism, confirmation in fetal blood was obtained in three, one of which presented as a pseudomosaic on the original amniotic fluid cell study. Fetal blood was also informative in two cases (one positive and the other negative) in which a diagnosis of the fragile X syndrome was being considered. Furthermore, when high risk pregnancies presented late in gestation (21–24 weeks), these methods allowed for a rapid cytogenetic diagnosis. The procedure has proved useful in most of these cases since the couples involved had indicated that they would probably have terminated the pregnancy without the reassurance of normal fetal lymphocyte studies. Since the technique carries a much higher risk of pregnancy loss than does amniocentesis, its use should only be considered when there are compelling indications.     

Inflammatory and immunological responses in skin and peripheral lymph of sheep following intracutaneous injection ofStaphylococcus aureus

The cellular response within lesions and in draining lymph was examined in sheep following a primary intracutaneous injection of live or killedS. aureus. Microscopic examination of sections from liveS. aureus lesions (12, 24, 48, and 96 h following vaccination) revealed a high ratio of neutrophils to macrophages at all times. This ratio was initially high following inoculation of killedS. aureus but decreased steadily at successive sampling times. Representative sections from lesions were subjected to indirect immunofluorescent staining to identify IgM-, IgG₁-, and IgG₂-containing cells. The ratio of IgG₂- to IgG₁-containing cells in lesions produced following liveS. aureus vaccination was significantly greater than the ratio in lesions produced by killed staphylococci. Lesions induced by liveS. aureus recruited significantly greater numbers of⁵¹Cr-labeled allogeneic neutrophils from blood than did lesions induced by killedS. aureus. During the first 6 h this difference was approx. 20-fold. The volume of lymph and the number of leukocytes draining liveS. aureus lesions was considerably greater than from lesions produced by killed staphylococci. The proportion of neutrophils in lymph draining both types of lesions increased markedly during the first two days of the response but was observed to be greater and remained higher for a longer period of time in lymph draining vaccine lesions produced following injection of live staphylococci. The increase in proportion of neutrophils in lymph was accompanied by a concomitant decrease in proportion of lymphocytes and macrophages. No immunoglobulin-containing cells or anti-staphylococcal antibody production was detected in lymph draining either type of lesion. These differences in inflammatory responses may contribute to the documented differences in immune responses to live and killed staphylococcal vaccines.