Marilyn S. Pollack

An update of congenital adrenal hyperplasia.

Publisher Summary nCongenital adrenal hyperplasia (CAH) is a family of disorders of adrenal steroidogenesis resulting from an inherited deficiency of one of several enzymes necessary for normal steroid synthesis. This chapter describes the recent advances in congenital adrenal hyperplasia. These advances have come from the interdisciplinary collaboration of embryologists, teratologists, enzymologists, immunogeneticists, population geneticists, steroid endocrinologists, and gender psychologists. The chapter describes asimplified scheme of adrenal steroidogenesis. It provides an overview of the additional evidence that supports the concept that the adrenal fasciculate and glomerulosa function as two separate glands. This has been gained from the recent study of patients with 21-hydroxylase deficiency. New data shows that in CAH, there is a 21-hydroxylation defect in the zona fasciculata of simple virilizers and salt wasters, whereas zona glomerulosa is defective in salt wasters and not in simple virilizers. The data suggest that there is one enzyme involved in the 21-hydroxylation of the 17-hydroxy and 17-deoxy pathways of adrenal steroidogenesis in zona fasciculata.

Differential inhibition of the MLR by iron: Association with HLA phenotype

The effect of iron on the MLR was examined by pretreating peripheral blood mononuclear cells from 77 unrelated Caucasians with five concentrations of Ferric-citrate (10.0 mM, 1.0 mM, 0.1 mM, 0.01 mM and 0.005 mM). After incubation with the metal, the cells were washed and cultured in a one-way MLR with a pool of stimulator cells. Cell viability remained unchanged (greater than 90 percent) during the 6-day culture period. Citrate per se had no effect on either the responder or the stimulator population. Iron treatment influenced the MLR in the following ways: (1) a variable degree of inhibition was observed which related to the dose of Ferric-citrate used and to HLA phenotype, (2) the responder but not the stimulator cells were affected, (3) no statistically significant differences were seen between female and male donor cells and (4) the mean percent response of cells from HLA-A2 donors were significantly (0.005<P<0.01) less susceptible to iron exposure than those from non-HLA-A2 individuals.The present results indicate that iron can interact with lymphoid cells and influence some immunological functions in vitro. The possibility is discussed that similar interactions take place in vivo which could contribute to the prognosis of certain diseases associated with particular HLA phenotypes.

Absence of HLA association or linkage for variations in sensitivity to the odor of androstenone

Sensitivity to the odor of 5-androst-16-en-3-one (androstenone), a testosterone metabolite, shows wide variations among unrelated individuals. Analysis of correlations in sensitivity between monozygotic twin pairs, dizygotic twin pairs, and nontwin sib pairs now shows that at least a portion of this variation is genetically determined. However, although data from some mouse studies have suggested a relationship between olfaction and the murine histocompatibility system (H-2), we were unable to demonstrate any role of the human HLA system in explaining the wide individual variations in human sensitivity to androstenone. An additional analysis of HLA antigens among 61 human mating pairs also provided no evidence that HLA phenotypes play a role in human mating preference. These data fail to support a role for the human HLA system in the recognition of an odorant of potential biological significance.

Different HLA antigen associations for the functionally active and inactive products of the complement C4F1 allele

The genetic polymorphism of the fourth component of human complement, C4, was studied in 945 unrelated Caucasian individuals. A third allele of the C4F (Rodgers) locus, termed C4F1 was demonstrated. This allele is characterized using immunofixation electrophoresis, by the presence of an additional fast-moving anodal band of C4 which distinguishes it clearly from the common C4F variant. The allelic frequencies fit the Hardy-Weinberg equilibrium assuming three alleles at the C4F locus: C4F, C4Fo, and C4F1. The functional activity of the C4F variants was investigated using a specific hemolytic overlay technique for C4. It was found that in almost all individuals (75 out of 78), the C4F1 allele codes for a functionally inactive C4 product only when it occurs on an HLA-B17 positive haplotype but that the same allele codes for a functionally active fast variant of C4 when it occurs on an HLS-B37 positive haplotype (18 out of 18). Very strong genetic linkage disequilibrium was observed for the C4F1 allele with HLA-B17 and B37. The active and inactive C4F1 variant also has marked nonrandom gametic association to different alleles of the Bf locus and to HLA-C locus determinants. No further variants of the C4S (Chido) locus have been identified so far. Rodgers (Rg) typing by the plasma inhibition test of anti-Rg antiserum has shown that plasma from individuals homozygous for the C4F1 allele is only able to partially inhibit anti-Rg whereas all C4F positive individuals totally inhibited the reaction.

Preliminary studies of the feline histocompatibility system.

It is often assumed that all vertebrate species possess a similar histocompatibility complex, responsible for allogeneic lymphocyte proliferation, intraspecies acute allograft rejection, and graft-versus-host reactions, and with highly polymorphic expression of both class I and class II molecules. However, there has been a conspicuous dearth of information relating to these types of functions and antigens among the felines. In a recent review of the major histocompatibility (MHC) system in man and animals, for example, van Dam (1981) discusses the systems of mouse, man, rhesus monkey, chimpanzee, guinea pig, rat, rabbit, Syrian hamster, chicken, dog, horse, swine, cattle, sheep, and goat, but fails to mention anything about cats. A computer search also fails to reveal any relevant literature. Analysis of what has been reviewed about the histocompatibility systems of other animals is also interesting because it reveals that not all vertebrates that have been studied actually have the same kinds of systems. In fact, while mice, dogs, guinea pigs, subhuman primates, and humans have well-studied MHC systems with the characteristics noted above, Syrian hamsters show little polymorphism in relation to class I antigens (Duncan et al. 1977, 1980). Among lower vertebrates, frogs have functions attributed to MHC determinants, but salamanders show essentially none of these functions (Cohen 1980). Likewise, bony fishes display acute allograft rejection, whereas the members of the relatively young reptile phylum do not (reviewed by Cohen and Collins 1977, Jonker and Balner 1980). Preliminary studies of the feline histocompatibility system that now indicate that this species of vertebrates may also have unusual expression of MHC characteristics are described in this report. Blood samples from the healthy, related and unrelated cats of various breeds used in these studies were collected by venipuncture of jugular veins at the Animal Medical Center, New York. Lymphocytotoxicity tests were performed using the standard 2-stage test (NIH Staff 1979) with 30 min incubation of cells at room temperature with test serum, followed by 60 min incubation with rabbit complement. Since all human sera tested were found to have a naturally occurring cytotoxic

Functional characteristics and differential expression of class II DR, DS, and SB antigens on human melanoma cell lines

Although most cultured melanoma cell lines express DR Class II molecules, many of these do not also express the DS (MB) Class II molecules as detected by a monoclonal antibody specific for DS. Cells lacking either DR or DS molecules or both could only be induced to express DR antigens in rare cases by combined incubations with azacytidine and Interleukin-2 conditioned medium, although the expression of DR molecules on fibroblasts or U937 monocytes could more easily be induced under the same culture conditions. Melanoma cells expressing DR antigens could function in antigen presentation for the histocompatibility antigens themselves and for DR specific presentation of TNP determinants to allogeneic T-cells sensitized to TNP modified lymphocytes and showing restriction in their responses to the specificity of the DR molecules expressed on the original, autologous sensitizing cells. DR positive melanoma cells could not, however, be demonstrated to function in the presentation of any of the soluble antigens tested. All DR positive melanoma cells also expressed SB antigens, but these were not detected on DR negative melanoma cells. These studies collectively indicate that the expression of Class II histocompatibility antigens on diverse cell types is subject to differential regulatory control and is associated with differences in their functional activities.

Ferrtin secretion by human mononuclear cells: Association with HLA phenotype☆

A number of different observations indicate that cells of the immune system can participate in the prevention of potential tissue toxicity from iron accumulation and that, in turn, iron and iron binding proteins have important effects on immune responses. The current studies were undertaken to examine a specific aspect of the interaction of iron with human peripheral blood mononuclear cells. A modified hemolytic plaque-forming assay was used to measure ferritin secretion in vitro by phytohemagglutinin activated or nonactivated mononuclear cells in response to stimulation by ferric citrate. Cells from 55 unrelated healthy subjects collectively representing all well-defined HLA-A, B, C, and DR antigens were studied. There were large reproducible differences in the numbers of plaques formed by different individuals, and there was a statistically significant increase in the frequency of the HLA determinant A3 among the low responders. Ferritin secretion measured with an antibody specific for acidic ferritin also showed a distinction between A3 and non-A3 donors. In preliminary cell mixing studies, ferritin secretion by mononuclear cells was shown to require the presence of monocytes and to be influenced by the secretion characteristics of both the monocyte and the T-cell donor. These results may provide a clue to the mechanism of development of idiopathic hemochromatosis which is an HLA-A-linked autosomal recessive disease associated with the specific HLA antigen HLA-A3.

Frequency of alloantibodies reacting with PHA-activated T lymphocytes, unexplainable by known HLA activities

Two hundred and three sera obtained from multiparous women were screened to determine the frequency of the appearance of antibodies reactive with PHA-activated T lymphocytes, but not with resting B or T cells from the same donor. The panel of cells on which the sera were tested consisted of lymphocytes from 38 unrelated donors known to be homozygous at the HLA-D locus. Forty-two sera were shown to react uniquely with PHA-activated T cells. The reactivities of these sera could not be explained in terms of the defined HLA-A,-B,-C, or DR antigen specificities on the panel cells, nor on the basis of known cross-reactivities among these antigens. Most of the antisera showed strong cytotoxicity with the activated T cells. Such sera may define antigens presented to the maternal immune system during differentiation and development, which are not expressed on adult T cells unless they are activated.

The biochemical basis for genotyping 21-hydroxylase deficiency

SummaryWe describe three different forms of 21-hydroxylase deficiency—classical congenital adrenal hyperplasia (CAH), late-onset 21-hydroxylase deficiency, and cryptic 21-hydroxylase deficiency—and we present hormonal standards by which to assign the appropriate 21-hydroxylase deficiency genotype for these disorders. The late-onset and cryptic forms of 21-hydroxylase deficiency are biochemically indistinguishable, although patients with the late-onset disorder present with marked clinical symptoms (e.g. virilization) whereas patients with cryptic 21-hydroxylase deficiency are clinically asymptomatic. Our latest studies suggest that late-onset 21-hydroxylase deficiency, like the classical and cryptic 21-hydroxylase deficiencies, is also genetically linked to HLA, the major histocompatibility complex of man. Our biochemical findings provide evidence that a spectrum of 21-hydroxylase deficiencies exist in the population.

HLA genotypes and HLA-linked genetic markers in Italian patients with classical 21-hydroxylase deficiency

SummaryHLA genotype and HLA-linked marker data for 40 unrelated patients from central Italy and 2 unrelated patients from Sardinia with congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21-OH-def) were analyzed. The results confirm that the HLA-linked 21-OH-def gene is associated with several different HLA determinants and complete HLA haplotypes, although the only determinant with significantly increased frequency was the complement C2 allele C2B. The HLA antigens B8 and DR3 were found in significantly decreased frequencies. The haplotype A3, Cw6, Bw47, BfF, DR7, which is exceptionally rare in the general population but which has been found in many other 21-OH-def patients from diverse geographical origins, was also found in one of the Italian patients. This and other HLA haplotype associations found among the Italian patients may represent mutations that have occurred on HLA haplotypes with genetic linkage disequilibrium or, alternatively, may represent mutations that have not yet had time to become randomly associated with different HLA complex determinants. The marked negative associations with B8 and DR3 could, however, result from an interaction between the gene products of the HLA complex and the 21-OH-def phenotype.