PubMed Health⌕ Search

Biomedical subjects

J Loon

Publications and source records attributed to J Loon.

11 recordsLinked to original sources
PubMed1994

A one-step monoclonal antibody typing procedure that simplifies HLA class I and class II typing.

We have developed monoclonal antibodies to most HLA specificities, making it possible for us to devise a simple, rapid, one-step microcytotoxicity test. The test is performed by adding 1 microliter of cells to 1 microliter of antibody-complement mixture predotted on the microtest tray. The reactions are read following a 1-hour incubation period (30 minutes in some instances). The analysis of reactions seen on testing 105 class I antibodies and 50 class II antibodies is shown. A comparison of typing by the standard NIH method and the new one-step procedure showed a > 96% concordance in the 500 T cells and 200 B cells we examined. Class I and class II typing could be performed using B cells, thus obviating the need to isolate both T and B cells for HLA typing.

Antibodies, Monoclonal↗
PubMed1987

Standardization of HLA through an international cell exchange.

1. In a series of 131 monthly distributions of lymphocytes from 4 persons each, tissue typing done on a blind basis of 486 persons was examined for a 12-year period. The number of participating laboratories was initially 85 and 285 in 1987. 2. It was found that 21 HLA-A,B specificities could be identified by 95-100% of the laboratories. An additional 19 specificities were correctly identified by 80-94%. Less than 80% concordance was found for 27 specificities. 3. All of the 4 new specificities assigned by the WHO committee in 1987 were identified previously by the cell exchange. 4. We conclude that this ongoing program aids tissue typing laboratories throughout the world to standardize their typing reagents, to detect new specificities, to monitor progress in international dissemination of the key sera for antigen definition, and to evaluate the state of development of tissue typing to applications in kidney transplantation.

HLA Antigens↗
PubMed1984

Ten-year progress report of the International Cell Exchange.

For the past 10 years, the International Cell Exchange has been a useful tool for testing rare and unusual HLA antigens and monitoring the progress in detection of recognized specificities. Of special interest are the antigens proposed in the 8th Workshop - 8w57, 8w58, 8w59, and 8w66. Marked improvement could be seen in the detection of 8w59 (29%) and 8w66 (31%). Possible new variants of the A9 and A10 complexes were tested in several exchanges. As shown by the increasing yearly average percentages of detection, laboratories are improving in their ability to type Aw23, Aw24, A25, A26, A29; Bw39, Bw41, Bw54, Bw55, Bw57, Bw58, Bw60 and Bw62. Over 90% of the laboratories are now able to detect Aw24; B5, B17, and B40, and A29 has attained the status of being well defined.

Cells↗
PubMed1983

Detection of Lewis a antigenic determinants in Chinese medicinal herbs.

Two Chinese medicinal herbs, Leonurus sibiricus L. and Carthamus tinctorius L., were found to have high levels of Lewis a (Lea)-like determinants. The water-soluble extracts specifically inhibited hemagglutination, hemolysis, and lymphocyte cytotoxicity directed against Lea. They did not inhibit Leb nor other specificities detected on lymphocytes, resulting from the interaction of Lewis, Secretor, and ABO systems such as A1Leb and A1Led. The activity was nondialyzable, resistant to boiling and proteolytic enzymes, but was destroyed by periodate. It was suprising that an Lea substance, previously found in human secretions, was also present in flower abstracts.

China↗
PubMed1982

HLA typing in non-Hodgkin's lymphomas. Comparative study in Caucasoids, Mexican-Americans and Negroids.

Over 200 cases of non-Hodgkin's lymphoma were typed for HLA-A, B, C and DR antigens, and typing was correlated with the morphologic diagnosis according to the Lukes-Collins classification system of non-Hodgkin's lymphomas. Three major racial groups were represented: Caucasoids, Mexican-Americans and Negroids. Significant associations were observed between HLA-AW33 and Caucasoid B-cell lymphomas, and for HLA AW24, HLA-B37 and HLA-B40 and B cell lymphomas in Negroids. No significant correlations were found within the Mexican-American patient population. The number of T cell lymphomas was insufficient to draw any conclusions. The DR antigens were not significantly associated with any of the diagnostic subgroups.

B-Lymphocytes↗
PubMed1982

Histocompatability antigens and immunoglobulin G insulin antibodies in Mexican-American insulin-dependent diabetic patients.

To determine the association of histocompatability antigens (HLA) with insulin-dependent diabetes (IDD) in Mexican-Americans, we determined HLA-A, -B, and -C specificities in 112 unrelated patients and 332 controls, and HLA-DR specificities in 85 patients and 209 controls. We also studied immunoglobulin G (IgG) insulin antibody formation in 56 Mexican-Americans with IDD, and the relationship between antibody formation and HLA-DR antigens. IDD patients have a significant increase in HLA-DR4 compared to the control population (chi 2 = 14.75; corrected P less than 0.0001). HLA-DR2 was not detected in any patient with IDD. A significant association between HLA-Aw30 and HLA-B18 was found in IDD patients (chi 2 = 9.39; P less than 0.05) as compared to controls. IgG insulin antibody formation was significantly increased in HLA-DR3- and -DR4-negative patients compared to that in patients positive for both antigens (P less than 0.05). These findings support previous observations in caucasians and black Americans indicating that HLA-DR specificities are associated with IDD and may play a role in determining its mode of inheritance, and perhaps its pathogenesis, independent of ethnic differences. HLA-DR immune-associated antigens are also of importance in determining IgG insulin antibody formation.

Adolescent↗
PubMed1981

Studies on the role of cellular immunity and genetics in the etiology of rapidly progressing breast cancer in Tunisia.

It has been suggested that poussée évolutive (PEV) or rapidly progressing breast cancer (RPBC) represents a failure in the host immune system to control the proliferation of breast cancer cells. To evaluate this possibility, we have performed in vivo and in vitro assays of cellular immunity in Tunisian patients with breast cancer. Studies of delayed hypersensitivity using microbial antigens and in vitro including lymphocyte transformation tests and measurements of B and T cells indicated that RPBC patients had an immune response comparable to that of breast cancer patients without evidence of rapid progression. Normal Tunisians were more immunocompetent, however, an appeared to have a higher level of immune activity than normal individuals in the United States. In a second, independent series, an increased frequency of blood group A was found in RPBC patients, suggesting a genetic predisposition to this form of breast cancer. However HLA typing for A, B and DRW antigens revealed no specific RPBC-associated HLA antigen. Our studies clearly demonstrate that RPBC, or PEV, is not a reflection of immunodeficiency.

Breast Neoplasms↗
PubMed1981

Loss of HLA-C locus specificities from stored lymphocytes and de novo synthesis following incubation at 37 degrees C.

The variable expression of the C locus specificities at the cell surface is a major problem in HLA typing and the phenomenon was clearly documented by the International Cell Exchange Program. In contrast with HLA-A and -B, the C locus specificities are readily lost from cells following storage at room temperature for a few days or in overnight incubation at 37 degrees C in the presence of protein synthesis inhibitors. These specificities can be made to reappear by making the cells metabolize at 37 degrees C for 8 to 20 h in nutrient medium. Sixty-nine per cent of the positive C locus reactions lost after 7-day storage at room temperature were recovered after overnight incubation at 37 degrees C. The reappearance was dependent on protein synthesis since presence of cyclohexamide during incubation completely blocked the recovery. A simple overnight incubation is very useful in enhancing C locus expression on older cells.

Epitopes↗
PubMed1980

HLA-DRw antigens in Mexican-American and Black-American diabetic patients.

HLA-A, - B, and -C antigens were studied in 67 Mexican-American and 38 black-American diabetic patients who had the onset of their disease before age 31 yr. Control populations consisted of 322 Mexican-American and 367 black-American subjects for HLA-A, -B, and -C antigens. In addition, HLA-DRw antigens were studied in 60 Mexican-American and 34 black-American diabetic patients. Control populations for HLA-DRw antigens consisted of 189 Mexican-American and 145 black-American subjects. We found that juvenile-onset--diabetic patients of Mexican-American origin who had the onset of their disease before age 19 demonstrated a significant increase in HLA-DRw4. HLA-DRw4 was also significantly increased in black-American patients with juvenile-onset diabetes mellitus. HLA-DRw2 was not detected in any patient with juvenile-onset diabetes in either ethnic group. A significant association was found between HLA-B18 and HLA-DRw3 in Mexican-American juvenile-diabetic patients. These findings, which are comparable to those in similar Caucasian patients, provide additional information to support the hypothesis that HLA-DRw antigens play a major role in determining the susceptibility to juvenile-onset diabetes mellitus.

Adult↗
PubMed1979

The biology of the HL-A system and the association with malignant lymphomas.

Present knowledge of the HL-A system as it relates to lymphoproliferative disease is reviewed briefly. Preliminary results from a current study demonstrate an elevated frequency of Aw33 and depressed frequency of B17 associated with non-Hodgkin's lymphoma-leukemia. In somewhat weaker association, Aw24 and Aw33 are elevated in follicular-center-cell lymphomas, while Bw44 is depressed. It is concluded that more specific subclassification of the lymphomas according to immunologic concepts may aid in correlating the disease with HL-A type as it has for Hodgkin's disease.

HLA Antigens↗