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C W DeWitt

Publications and source records attributed to C W DeWitt.

At least 19 recordsLinked to original sources
PubMed1992

Possible association of the extended MHC haplotype B44-SC30-DR4 with autism.

We previously reported that the complement C4B null allele appears to be associated with infantile autism. Since the C4B null allele is known to be part of the extended or ancestral haplotype [B44-SC30-DR4], we investigated the incidence of [B44-SC30-DR4] in 21 autistic children and their parents. This extended haplotype was increased by almost six-fold in the autistic subjects as compared with healthy controls. Moreover, the total number of extended haplotypes expressed on chromosomes of autistic subjects was significantly increased as compared with those expressed on chromosomes of healthy subjects. We conclude that a gene related to, or included in, the extended major histocompatibility complex may be associated with autism.

Adolescent↗
PubMed1992

Outcome of cardiac transplant recipients with a positive donor-specific crossmatch--preliminary results with plasmapheresis.

To assess the influence of a positive T or B cell IgG crossmatch on the development of rejection and mortality following cardiac transplantation, we reviewed all cardiac transplants performed in Utah between March 1985 and October 1990. Of the 328 cardiac allograft recipients, 11 (3.4%) had an IgG positive crossmatch. Actuarial survival at 24 months in the positive crossmatch group was 57.3% +/- 0.02 while that of the controls was 86.1% +/- 2.1 (P < 0.05). Allograft rejection occurred earlier in recipients with a positive crossmatch (10.0 +/- 5.8 days versus 34.0 +/- 2.3 days, P < 0.001). The first allograft rejection episode in patients with a positive crossmatch was characterized by immunoglobulin and complement deposition in small blood vessels and interstitial edema and endothelial cell activation in the absence of a lymphocytic infiltrate. Furthermore, the allograft rejection in the positive crossmatch group was accompanied by hemodynamic compromise in a large proportion of the patients (73%). In addition to augmentation of immunosuppression, plasma exchange therapy was performed within the first week following transplantation in 8 of the 11 positive crossmatch patients. Survival in the patients treated with plasma exchange (75%) appears to be better than in those not receiving plasma exchange (33%) within one week of transplantation. While immunosuppressive therapy aimed at the humoral arm of the immune system and plasma exchange therapy may improve survival in recipients with a positive donor-specific crossmatch, survival is worse in patients with a positive crossmatch than in patients with a negative crossmatch. Thus, it would appear prudent to prospectively crossmatch cardiac transplant candidates with a greater risk of developing a positive crossmatch, such as those potential recipients with an elevated level of panel-reactive antibodies.

B-Lymphocytes↗
PubMed1990

Relationship of OKT3 sensitization and vascular rejection in cardiac transplant patients receiving OKT3 rejection prophylaxis.

We prospectively and serially monitored plasma levels of OKT3 in 20 patients who were receiving 14- or 21-day rejection prophylaxis with OKT3. We retrospectively compared plasma OKT3 levels with biopsy scores assessed by light microscopy and immunofluorescence, clinical findings, human antimouse antibody (HAMA) production assessed by a blocking assay and by ELISA, and circulating immune complex levels assessed by a flow cytometric Raji cell assay. Using these methods, we evaluated the relationship of OKT3 sensitization, a humorally mediated immune response, to the development of vascular rejection in these patients. We found that 6 of 20 patients had declines in plasma OKT3 levels to less than 50% of their steady-state value before the conclusion of therapy (OKT3 consumption). This fall in plasma OKT3 preceded a significant rise in the CD 3 lymphocyte level by up to 3 days. All 6 patients showed HAMA production by either blocking or ELISA assay (P = less than 0.02) and developed vascular rather than cellular rejection (P = less than 0.01). OKT3 sensitization was significantly more common in patients treated with 21-day rejection prophylaxis (4 of 6 patients, P = less than 0.01). Only 4 of 14 other patients showed vascular rejection; 2 of these 4 also developed HAMA without OKT3 consumption and both had been treated with 21-day rejection prophylaxis with OKT3. None of the 20 patients showed significant levels of circulating immune complexes. This study demonstrates that OKT3 sensitization is strongly associated with vascular rejection. Vascular rejection was usually demonstrated 7 days after OKT3 consumption was seen and was coincident with HAMA production. By contrast, 4 patients without OKT3 sensitization had vascular rejection demonstrable in the early posttransplant period; in such patients, prospective immunofluorescence of biopsies was the only reliable indicator of this rejection type. The higher incidence of vascular rejection in these 20 patients was definitely related to the use of 21-day OKT3 rejection prophylaxis. Overall, 7 of the 12 patients treated with this regimen developed vascular rejection. Allograft and patient survival among patients with vascular rejection was significantly worse than in patients with cellular rejection (P = less than 0.01). Prospective monitoring of patients treated with OKT3 by serial plasma levels and by biopsy immunofluorescence will identify patients at risk for these types of humoral rejection.

Antibodies, Anti-Idiotypic↗
PubMed1989

Efficacy of OKT3 retreatment for refractory cardiac allograft rejection.

Although OKT3 monoclonal antibody is a useful therapy for refractory cardiac allograft rejection, the use of OKT3 for prophylaxis may be limited by the potential of sensitization and subsequent loss of efficacy on retreatment. OKT3 was required for refractory rejection in 21 of 165 recipients transplanted between March 1985 and August 1988. Twelve of these patients had previously been exposed to OKT3, and the retreatment efficacy was evaluated. The study population averaged 42.1 +/- 15.3 years of age (mean +/- SEM) and had experienced 2 +/- 1 previous episodes of rejection. The prior episodes of rejection had been treated with pulse methylprednisolone and antithymocyte globulin, and in addition 3 patients (25%) also required a course of antilymphoblast globulin. Retreatment OKT3 for refractory rejection was required 120 +/- 94 days following transplantation. CD3+ lymphocytes were eliminated from the circulation within 24-48 hr in 11 of 12 patients, all of whom showed histologic improvement within the first week. Total resolution on the initial follow-up biopsy was noted in 9 (75%) during the course of therapy. Subsequent rejection episodes occurred in 9 (82%) of the survivors at 71 +/- 64 days. One-year survival was 83% in this vigorously rejecting patient population. Serious infections occurred within 3 months of therapy in 4 (36%). The side effects of OKT3 retreatment were similar to those seen with first exposure and did not require OKT3 discontinuation. Thus OKT3 may be administered with success in most patients who have previously been exposed to it.

Adult↗
PubMed1984

HLA A, B and DR typing in idiopathic dilated cardiomyopathy: a search for immune response factors.

Several autoimmune diseases have been associated with increased frequencies of various histocompatibility antigen (HLA) types that may be linked to immune response genes. Idiopathic dilated cardiomyopathy (IDC) has been proposed as a disease with autoimmune features, but HLA associations have not been evaluated. We performed HLA typing in 37 consecutive patients with IDC. Patients with habitual alcoholism were excluded. Results showed that no single HLA type could account for most cases; IDC is a genetically heterogeneous disease. However, uneven distributions were noted for certain types. Haplotype frequency of B27 was 0.145 in patients vs 0.033 in 5,726 local control subjects (p less than 0.001). Other A and B frequencies (except A2) were evenly distributed. HLA DR typing also revealed differences. The DR4 locus was present in 54% (19 of 35) of patients, vs 32% (26 of 82) of blood bank control subjects (p less than 0.02). The associated relative risk of DR4 was 2.2 and the etiologic fraction 0.29. Sex, disease chronicity, functional class, ejection fraction and biopsy evidence of myocarditis did not distinguish DR4-positive from DR4-negative patients, but they were older (54 +/- 12 vs 42 +/- 14 years, p less than 0.02). Of note, 68% were positive for DR4 or B27, or both. HLA DR6Y was underrepresented; it was present in 9% (3 of 35) of patients, vs 26% (21 of 82) of control subjects (p less than 0.04). The relative risk of DR6Y was 0.27 and the preventive fraction 0.19. These associations will require independent confirmation. However, they suggest that genetically determined immune response factors associated with HLA loci may play a role in pathogenesis in certain patients with IDC.

ABO Blood-Group System↗
PubMed1984

Genetic control of collagen-induced arthritis in rats: the immune response to type II collagen among susceptible and resistant strains and evidence for multiple gene control.

We evaluated the cellular and humoral immune response to type II collagen and the relative susceptibility to type II collagen-induced arthritis (CIA) in 14 inbred rat strains representing six RT1 specificities and including four congenic strain pairs differing only at RT1, by using a standard protocol with native calf type II collagen as the immunogen: WF(RT1u) was a high responder and susceptible; RT1c , RT1a , and RT1l strains were intermediate responders and, on a strain basis, were variably susceptible or resistant; RT1b and RT1n strains were low responders and resistant to CIA. An intermediate to high immune response to type II collagen, although associated with CIA, was not sufficient for the induction of clinical arthritis. A high degree of cross-reactivity between calf and rat type II collagen was found. No selective, antigen-specific decrease in immune response to rat type II collagen as compared to calf type II collagen was found in the resistant strains. In six strains, resistance correlated with the expression of public Ia antigens cross-reactive with the public Ia antigens of BN. The non-MHC-linked BN genome also exerted a suppressive effect on the incidence and severity of CIA in strains carrying collagen-responder and CIA-susceptible RT1 alleles. Together, the data show that CIA in rats is under the control of multiple genes, both RT1-linked and nonlinked .

Animals↗
PubMed1984

Modulation of collagen-induced arthritis in rats by non-RT1-linked genes.

An immunogenetic analysis of the progeny of F1, F2, and (F1 x parental strain) test cross-matings between the CIA-susceptible DA(RT1av1) and the CIA-resistant BN(RT1n) rat strains was performed. Hybrid progeny were tested for susceptibility to CIA as induced by native calf type II collagen, and for immune response to native rat and calf type II collagens. The results show a minimum of one non-RT1-linked gene which modifies susceptibility to CIA in RT1a/a hybrid progeny. These hybrids have anti-collagen immune responses equivalent to those of the parental DA strain as measured by skin testing and IgG antibody titers. An affect of sex hormones on susceptibility to CIA is indicated, because hybrid females were more susceptible than were hybrid males of equivalent RT1 allotypes.

Animals↗
PubMed1981

Immunogenetic control of experimental type II collagen-induced arthritis. I. Susceptibility and resistance among inbred strains of rats.

Seven inbred rat strains were tested for susceptibility to experimental type II collagen-induced arthritis and for development of cellular immunity to type II collagen by delayed hypersensitivity skin testing. WF (RT1u), LEW (RT1l), and DA (RT1a) were the most susceptible of the strains tested with respect to incidence (greater than 95%) and severity of disease. LEW and DA were strongly skin test reactive to calf type II collagen. BUF (RT1b) developed moderate skin test responses to calf type II collagen and showed low susceptibility to collagen arthritis (1/8). MAXX (RT1n), LEW.B3 (RT1nvl), and AUG (RT1c) were not susceptible to collagen arthritis and showed negative to very weak skin test responses to type II collagen. Disease susceptibility was inherited as a dominant trait in the F1 progeny of (WF X LEW.B3) matings. These data suggest that clinical expression of experimental collagen-induced arthritis and immune responsiveness to type II collagen are controlled in part by genes within or closely linked to the rat major histocompatibility complex--RT1.

Animals↗
PubMed1981

Immunogenetic control of experimental collagen-induced arthritis in rats. II. ECIA susceptibility and immune response to type II collagen (CALF) are linked to RT1.

The segregation of genes controlling ECIA susceptibility and the level of immune response to native calf type II collagen were determined in the F2 progeny of matings between WF (RT1u/u; ECIA-susceptible; high responders) and LEW.B3 (RT1n/n; ECIA-resistant; low to intermediate responders). RT1n/n F2 progeny showed resistance to ECIA, low skin test reactivity to type II collagen and intermediate levels of IgG anti-collagen antibodies (-log2 of 6.2 +/- 2.6; mean +/- SD, n = 10). RT1u/u and RT1u/n F2 progeny were susceptible to ECIA and were high responders to type II collagen by skin testing and IgG antibody titres (-log2 of 12.1 +/- 1.3, mean +/- SD, n = 26). Although all rats that developed arthritis were also high responders to type II collagen one group of immature F2 progeny, RT1u/u and RT1u/n, showed high anti-collagen immune responses in the absence of detectable arthritis. The data indicate that genes linked to RT1.A control susceptibility to ECIA and at least part of the immune response to native calf type II collagen in WF and LEW.B3 rats.

Animals↗
PubMed1981

Ultraviolet light induces tumors with both unique and host-associated antigenic specificities.

Murine tumors induced by ultraviolet light (UV) are immunogenic in syngeneic and semi-syngeneic hosts, evoking antibody of several different specificities. Cytotoxic antibody specific for the immunizing syngeneic tumor (tumor-specific antigen) comprises the early response and a minor portion of the later response of C3H and C3H.SW mice. It is the primary specificity to which C57BL/6 and C57BL/10 hosts respond. The major portion of the antibody produced by C3H and C3H.SW against syngeneic tumors cross-reacts strongly with other tumors, both UV and chemically induced, arising in C3H and C3H.SW but not in B6.H2k, C57BL/6, C57BL/10, or (C3H X B6)F1. Normal adult cells or embryonic fibroblasts do not cross-react with the antisera. These results are interpreted as evidence for the involvement of a host component (non-MHC) in this tumor-associated antigen (TAA). (C3H X B6)F1 and (C3H X BALB/c)F1 hosts respond to C3H tumors with antibody with cross-reactive specificities identical to those of the C3H and C3H.SW hosts. thus detecting the TAA(C3H) specificity. (C3H X B6)F1 hosts respond to syngeneic F1 tumors, however, with a totally cross-reactive antibody that is interpreted as evidence for the existence of a common antigen in addition to the evident immune response control. An undetected TAA (B6) specificity in the (C3H X B6)F1 tumors is speculatively proposed.

Absorption↗
PubMed1980

The LEW.BN(2R) strain: a recombinant in the rat MHC.

Cell-mediated cytolytic (CMC) responses resulting from immunizations between rat strains considered to be RT1 (Ag-B) identical (LEW.B3:BN) are capable of detecting a membrane determinant(s) controlled by a locus linked to RT1, which has been designated Ag-L. The Ag-L gene region has been isolated in a recombinant line, tentatively designated as LEW.BN(2R), and has been assigned the RT1r5 haplotype. The data presented demonstrate that the genes responsible for MLR stimulation in the 2R strain are of LEW origin. In addition, LEW.B3 anti-BN CTL appear to recognize multiple specificities, only one of which is in the 2R strain. Some of the remaining specificities in BN may be the result of interactions between undetected genes that have been separated in the LEW.B3 and 2R strains.

Alleles↗
PubMed1980

Analysis of cytotoxic effector cell populations by kinetic and monolayer adsorption techniques.

Cytolytically active lymphocytes were generated by immunizations between rat strains and evaluated by both kinetic and monolayer adsorption techniques. Kinetic analysis yields two values (Ka and Vmax), which are characteristic of interactions between individual effector and target cell populations. The Ka values this obtained correlate with the quantitative level of adsorption of CTL onto cellular monolayers, and we conclude that Ka is a measure of the binding avidity of effector and target cells.

Animals↗