Developmental changes in the presence of specific chicken fetal-leukemic antigen determinants in the chicken, Japanese quail, and the interspecific hybrid

Chicken developmental antigens: analysis of erythroid populations with monoclonal antibodies

Fusions were performed between the mouse PAI myeloma cell line and spleen cells from Balb/c mice immunized with intact erythrocytes from 1-day Cornell K-strain White Leghorn chickens. Following single cell cloning, four hybridoma clones were found to secrete erythroid specific monoclonal antibodies. Based on its pattern of reactivity, the antibody (IgG2a, kappa) secreted by clone 10C6 detects a specific avian oncodevelopmental antigen associated with the hematopoietic system: chicken fetal antigen (CFA). Two other clones, designated as 3F12 and 4C2, produced antibodies (IgM, kappa) that recognize another avian developmental antigen: chicken adult antigen (CAA). A fourth clone, 9F9, produced an antibody (IgM, kappa) that reacts with all peripheral erythrocytes from both Japanese quail and chicken regardless of age. Clone 10C6 antibody apparently detects an erythrocyte specific (ES) determinant of CFA associated with determinant #8 while antibodies of clones 3F12 and 4C2 recognize a chicken specific determinant of CAA. Analysis by complement mediated microcytotoxicity indicated that the epitopes detected by 10C6 vs 3F12 and 4C2 antibodies were expressed on erythrocytes in a reciprocal fashion during development. Furthermore, strain variations in the incidence of erythrocytes carrying these epitopes were observed. The usefulness of these monoclonal antibodies for the study of erythroid populations is discussed.

Hematopoietic differentiation cell surface antigen switching in the bone marrow of different aged chickens

Immune cytolysis and immunofluorescence were used to examine chicken fetal antigen CFA) and chicken adult antigen (CAA) expression on the differentiation/maturation series of definitive erythroid cells obtained from the bone marrow of different aged chickens. We found that erythroid cells undergo changes in CFA/CAA antigenic expression dependent on their differentiation/maturation stages as well as the developmental age of the chicken. All differentiation/maturation stages of erythroid cells in the bone marrow of 12 and 18-day-old embryos express CFA only. Erythroblasts obtained from 7-day post-hatched chickens express either CFA or CAA. All three CFA/CAA phenotypes (i.e., CFA, CAA, and CFA + CAA) are observed in subsequent maturation stages, but only the CFA + CAA phenotype is observed in mature erythroid cells in the bone marrow of 7-day post-hatched chickens. Erythroblasts from 62 day post-hatched chickens exhibit all three CFA/CAA phenotypes. Cells in the subsequent maturation stages express various CFA, CAA, or CFA + CAA phenotypes resulting in a majority of the mature erythrocytes expressing both CFA and CAA, and a small population of mature erythrocytes expressing CAA only. Erythroblasts from adult chickens express both CFA and CAA; however, CFA is lost during erythroid maturation resulting in mature erythrocytes which express CAA only. These studies indicate that both the erythroid differentiation/ maturation stage and the developmental age of the chicken influence CFA and CAA antigenic expression on erythroid cells undergoing cellular differentiation/maturation in the bone marrow.

Monosaccharides define two immunodominant structures of chicken fetal antigen

Chicken fetal antigen (CFA) is an oncodevelopmental antigen associated with hematolymphoid development and differentiation. The immunodominant structures of two CFA determinants were characterized by hapten inhibition of microcytotoxicity (HIM) and were found to be defined by specific monosaccharides. CFA determinants 5 and 11 were effectively (greater than 50%) inhibited by D-mannose and D-glucose, respectively. Therefore, these carbohydrate residues, or closely related structures, are proposed as the immunodominant structures for these antigenic determinants. Implications of these results vis à vis the developmental control and biological role of CFA are discussed.

Quail fetal antigen (QFA): identification and comparison with chicken fetal antigen

Quail fetal antigen (QFA), an analogous hematopoietic antigen to chicken fetal antigen (CFA), was identified and shown to be a developmental antigen on the blood cells of Japanese quail and other avian species. Rabbit antiserum against 14-day embryonic quail red blood cells (RBCs) was specifically adsorbed to achieve fetal specificity and to eliminate any cross reactivity with the CFA system. Complement-mediated microcytotoxicity and hemagglutination assays were used to detect the presence of QFA on hematopoietic cells. QFA was found on 100% of the peripheral RBCs from 10-day quail embryos but incidence of the antigen gradually declined with increasing development. Complete loss of QFA from RBCs occurred just prior to sexual maturation between 31 and 42 days of age. No qualitative differences in erythroid expression of QFA were observed during development; however, RBCs from both embryonic duck and interspecific quail- chicken hybrids reacted with R-anti QFA. Like CFA, quail fetal antigen was associated with lymphocytes, particularly those from primary lymphoid organs. Similarities in the developmentally controlled tissue distribution of QFA and CFA suggest that developmental hematopoietic antigens are a common feature of avian species and are useful cell surface markers for studies of development and differentiation.

Chicken fetal antigen: association with lymphoid development and differentiation

Rabbit antisera capable of detecting chicken fetal antigen (CFA) was prepared against 1-day chick red blood cells (RBCs) and made specific by exhaustive adsorption with adult chicken peripheral RBCs (PRBCs) from the same strain. Microcytotoxicity was used to study the incidence of CFA on lymphocytes obtained from several organs at different developmental stages in the chicken. Lymphocyte-associated CFA (LA-CFA) determinants and erythrocyte-specific CFA (ES-CFA) determinants were distinguished through the use of adsorption analysis. The high incidence of CFA-positive lymphocytes found in the fetal bursa and thymus was not equaled in the peripheral organs of the spleen, cecal tonsils, and gland of Harder. CFA expression on adult lymphocytes was restricted to the thymus and peripheral blood. It is suggested that these cells may represent a subpopulation of T lymphocytes. Adult spleen, cecal tonsils, and gland of Harder were virtually devoid of CFA-bearing lymphocytes. At fetal developmental stages when greater than 94% of the bursal B cells were CFA-positive, few, if any, of the highly differentiated Harderian B cells possessed CFA. It is suggested that LA-CFA expression is dependent upon B cell differentiation and/or the bursa (central) vs gland of Harder (peripheral) microenvironment. The pattern of CFA expression on bursacytes is discussed in light of the properties of age resistance and bursal-dependent target cells associated with virally induced lymphoid leukosis.