Transfer of agammaglobulinemia in the chicken. I. Generation of suppressor activity by injection of bursa cells

Spleen cells from adult agammaglobulinemic (bursectomized) chickens taken 1 to 3 weeks after an injection of histocompatible bursa cells can inhibit the adoptive antibody response to B. abortus of normal spleen or bursa cells in irradiated recipients. Spleen cells from Aγ chickens not injected with bursa cells generally do not. Moreover, bursectomized chickens which have been reconstituted with spleen cells within the first week after hatching do not respond with suppressor cell formation upon bursa cell injection. This apparent “autoimmunization” with bursa cells induces suppressor T cells which are only minimally sensitive to treatment with mitomycin C or to 5000 R γ irradiation. The suppressor activity is neither induced nor potentiated by concanavalin A in vivo. It is much stronger in spleen than in thymus cells and appears to be macrophage independent and to require intact cells. The cell component which stimulates the suppressor activity is more pronounced on bursa than on spleen cells, and is at most present to a very limited extent on bone marrow, thymus, or peritoneal exudate cells. It is better represented in comparable cell numbers of Day 17 than of Day 14 embryonic bursa. The inducing cell component is present in the membrane fraction of disrupted bursa cells. Immunization with bursa cells from B locus histoincompatible chickens leads to suppressor activity against histocompatible bursa cells. Although the removal of Ig-bearing cells from bursa greatly diminishes its immunizing capacity, injection of serum IgM and IgG does not induce suppressor cells. It is suggested that tolerance to a B-cell antigen is lacking in adult Aγ chickens, resulting in an autoimmune response upon exposure to B cells. The B-cell antigen may be a cell surface-specific form of Ig, a complex of Ig and a membrane component, or a differentiation antigen which appears simultaneously with Ig during ontogeny.     

Evidence for an IgD homologue on chicken lymphocytes

Chicken lymphocyte membrane immunoglobulins (Ig), were precipitated with mouse monoclonal antibodies specific for heavy and light chain isotypes and analyzed by polyacrylamide gel electrophoresis. Very little or no membrane-bound IgG and IgA was detected. After sequential precipitation and removal of IgM reactive with any of three monoclonal anti-mu antibodies, anti-light chain antibody precipitated residual Ig with a relative electrophoretic mobility similar to that of IgM. Under reducing conditions, these surface Ig molecules had a heavy chain that appeared slightly larger (approximately 81,000 daltons) than mu-chain (approximately 79,000 daltons), and light chains of approximately 25,000 daltons. Complete clearance of membrane-bound IgM reactive with an anti-mu allotype antiserum left similar molecules precipitate by monoclonal anti-light chain antibody. These non-IgM molecules could be detected on the surface of lymphocytes from blood, spleen, bursa and the B cell line RAV-1, but not from thymus or blood from an agammaglobulinemic chicken. After capping of B cell surface IgM with anti-mu, immunofluorescent staining with anti-light chain antibody revealed residual Ig molecules disturbed across the surface of more than 90% of the IgM-bearing cells. The data suggest the existence of an avian homologue of mammalian IgD. Affinity-purified goat anti-mu antibodies and a fourth monoclonal anti-mu antibody reacted with both IgM and the putative IgD molecules, which suggests that the IgD homologue shares at least one common determinant with chicken IgM.     

B cell maturation in the chicken Harderian gland

We have characterized maturation of B lymphocytes in the chicken Harderian gland. Expression of Ig genes was studied by using lambda L and mu H chain-specific DNA probes. In unstimulated chickens, the concentration of mu H chain and lambda L chain mRNA in the Harderian gland was observed to be greater than 8 times higher than in the bursa of Fabricius or spleen. By using in situ hybridization, the plasma cells expressing mu mRNA were located in central area of the gland packed around the tubules. Antibodies produced by the Harderian plasma cells were measured from the tears before and after antigenic stimulation. In unstimulated chickens high levels of total IgM, IgA, and IgG were observed. After ocular stimulation with tetanus toxoid, specific antitetanus IgG and IgA antibodies appeared in the tears but IgM antibodies were barely detectable. These results indicate that after antigenic stimulation the Harderian B cells rapidly mature through IgM secretion to the production of IgG or IgA. Southern blot analysis of the Harderian total genomic DNA showed strong rearrangement in the lambda L chain locus. In contrast, the band indicating major rearrangement in the mu H chain locus gave a very poor hybridization signal, indicating deletion of C mu genes in the Harderian gland DNA. As a conclusion, our present data indicate for the Harderian gland a role in terminal B cell differentiation and Ig class switch.     

Dietary conjugated linoleic acid increases immunoglobulin productivity of Sprague-Dawley rat spleen lymphocytes

The dietary effects of conjugated linoleic acid (CLA) on Ig production of Sprague-Dawley rats were examined at various doses such as 0 (control), 0.05, 0.10, 0.25, and 0.50%. CLA increased IgG and IgM production of spleen lymphocytes in a dose-dependent manner, and these levels reached a plateau at 0.25%. IgA production was not detected in the control group, while it was detected in all CLA-fed groups and IgA productivity of spleen lymphocytes increased in a dose-dependent manner at the doses from 0.05 to 0.50%. Dietary CLA did not affect serum Ig levels. The major fatty acid composition of spleen lymphocytes was not affected by dietary CLA, which itself was hardly incorporated into the cells. In an in vitro assay, the effects of CLA and its oxidative derivatives, furan type fatty acids, on Ig productivity were also examined. As a result, 100 microM CLA suppressed Ig production of spleen lymphocytes and the degree was as follows IgA > IgG > IgM. Each CLA isomer and the furan type fatty acids also suppressed Ig production but the degree was weaker than the mixture of CLA isomers. In this result, dietary CLA increased Ig productivity of spleen lymphocytes in vivo.     

In vitro and in vivo activation of murine gamma/delta T cells induces the expression of IgA, IgM, and IgG Fc receptors.

The present studies examined resting and activated murine gamma/delta T lymphocytes, in vitro and in vivo, for surface expression of FcR. Polyclonal gamma/delta TCR+ lymphocytes selectively grown from the spleen and intestine of normal mice did not express FcR when the cells were in a resting state, but when cells were activated with anti-CD3 antibody virtually all of the splenic gamma/delta lymphocytes and a large subpopulation of the intestinal gamma/delta lymphocytes expressed IgA and IgM FcR. This was confirmed by using transgenic mice. Resting gamma/delta TCR+ lymphocytes from the spleen, thymus, lymph node, and blood of gamma/delta TCR transgenic mice did not express FcR for any of the five major classes of Ig H chains. Activation of the gamma/delta TCR+ cells via the CD3/TCR complex induced high levels of IgM and IgA FcR and low levels of IgG FcR. Finally, in hepatic granulomas of schistosome-infected mice, activated gamma/delta TCR+ cells are present and express high levels of IgA and IgM FcR and low levels of IgG FcR. These investigations establish that transition of gamma/delta TCR+ lymphocytes from a resting to an activated state (triggered via the T3Ti TCR complex) is accompanied by the induction of surface membrane receptors specific for Ig H chain isotypes. The activation-linked expression of FcR on gamma/delta TCR+ lymphocytes provides potential mechanisms for coupling the functional activities of gamma/delta T lymphocytes with immune mechanisms that involve Ig molecules, such as antibody-dependent cellular cytotoxicity.     

Tissue distribution of immunoglobulin-secreting cells in normal and IgA-deficient chickens.

A reverse hemolytic plaque assay was employed to enumerate lymphoid cells actively secreting either immunoglobulin (Ig)G, IgA, or IgM in the small intestine, lungs, and lymphoid organs of normal and IgA-deficient chickens. In normal birds, intestinal lamina propria lymphocytes were proportionately richest in cells secreting IgG and IgA whereas the bone marrow was richest in IgM-secreting cells. The highest ratio of IgA to IgG secreting cells was also found in the lamina propria lymphocytes of the intestine (0.9), followed by the IgA to IgG ratios in the intestinal epithelium (0.31), and the lungs (0.19). The IgA to IgG ratios in the bone marrow (0.08) and the spleen (0.02) were considerably lower. Thus, both the intestine and the lungs were relatively enriched in cells actively secreting IgA. These IgA-secreting cells are the likely source of the IgA found in such quantities in intestinal and respiratory secretions. The tissue distribution of Ig-secreting cells was also studied in two generations of birds with experimentally induced IgA deficiency. There was a striking diminution of IgA-secreting cells in all tissues, including the intestine and lungs, whereas cells secreting IgG and IgM were normal or increased. The lack of IgA-secreting cells in these birds represents the effects of donor suppressor T cells having specificity for IgA.     

Cell surface antigens expressed by subsets of pre-B cells and B cells

A large number of monoclonal antibodies, produced by immunizing rats with mouse pre-B cell lines, have been analyzed for their ability to define cell surface antigens expressed by B cells at early stages of differentiation. Whereas many antibodies recognized antigens on pre-B cell lines, only two clones detected cell surface antigens that were distinguished by their restricted distribution among a panel of continuous cell lines and cells from various tissues. Monoclonal antibody clone AA4.1 recognized a cell surface antigen found on all pre-B lymphomas and on one of three B lymphomas tested. This antigen was found on cells at highest frequency in the bone marrow. Adult spleen and fetal liver also have detectable numbers of AA4.1+ cells. Cells that did not express this antigen include plasmacytomas, two of three B lymphomas, T lymphomas, a stem cell line, adult liver, brain, thymus, and lymph node cells. Clone GF1.2 detected an antigen on some pre-B cell lines, one of three B lymphomas tested, and a small fraction of cells from adult bone marrow, spleen, lymph node, and fetal liver. Plasmacytomas, some pre-B lymphomas, two B lymphomas, T lymphomas, adult liver, brain, and thymus cells were negative. In adult bone marrow, AA4.1 bound to all cytoplasmic IgM+ pre-B cells, whereas GF1.2 detected one-half of these cells. Both antibodies recognized approximately 50% of surface IgM+ (sIgM+) bone marrow cells. A small population of bone marrow cells lacking any detectable Ig (surface or cytoplasmic) also reacted with these antibodies. Depletion of AA4.1 or GF1.2 antigen-bearing cells from bone marrow reduced the ability of bone marrow B cells to respond to LPS by 50 to 65%. Experiments with a cloned pre-B lymphoma demonstrate that AA4.1+ pre-B cells become sIgM+ GF1.2+ B cells after activation with LPS. These antibodies recognize cell surface determinants with restricted distribution among the B lymphocyte lineage because they detect antigens displayed by normal and transformed immature B lymphocytes.     

AT-1.1: A thymus-specific alloantigen of chickens

A thymocyte-specific alloantigen, designated AT (avian thymus) –1.1, has been detected in Cornell C strain (CS) and Obese strain (OS) chickens, the latter being a strain derived from CS which develops a spontaneous form of autoimmune thyroiditis (SAT). Antisera specific for this antigen were developed first in a turkey immunized with thymocytes from an OS chicken and, later, in AT-1.1-negative CS chickens immunized with AT-1.1-positive thymocytes. AT-1.1 was detected in 50–70% of cells in a thymus cell suspension, but was not seen on peripheral blood lymphocytes, erythrocytes, or cells from bursa, spleen, kidney, liver, or brain. It was present on thymocytes of chickens at all ages tested, from 1 day to 6 months of age. AT-1.1 was not detected in six chicken lymphoid tumor cell lines tested, and birds expressing it were found to be negative for the presence of Marek's disease viral antigens. Pedigree studies on 287 (OS × CS)F₂ chickens demonstrated that AT-1.1 is expressed in a dominant or codominant manner, and the gene coding for this antigen was not linked to the B (major histocompatibility) complex. The genetics and tissue distributions of AT-1.1 indicate that it differs from thymus cell surface antigens, avian or mammalian, previously described.     

Dietary Conjugated Linoleic Acid Increases Immunoglobulin Productivity of Sprague-Dawley Rat Spleen Lymphocytes

The dietary effects of conjugated linoleic acid (CLA) on Ig production of Sprague-Dawley rats were examined at various doses such as 0 (control), 0.05, 0.10, 0.25, and 0.50%. CLA increased IgG and IgM production of spleen lymphocytes in a dose-dependent manner, and these levels reached a plateau at 0.25%. IgA production was not detected in the control group, while it was detected in all CLA-fed groups and IgA productivity of spleen lymphocytes increased in a dose-dependent manner at the doses from 0.05 to 0.50%. Dietary CLA did not affect serum Ig levels. The major fatty acid composition of spleen lymphocytes was not affected by dietary CLA, which itself was hardly incorporated into the cells. In an in vitro assay, the effects of CLA and its oxidative derivatives, furan type fatty acids, on Ig productivity were also examined. As a result, 100 μM CLA suppressed Ig production of spleen lymphocytes and the degree was as follows IgA>IgG>IgM. Each CLA isomer and the furan type fatty acids also suppressed Ig production but the degree was weaker than the mixture of CLA isomers. In this result, dietary CLA increased Ig productivity of spleen lymphocytes in vivo.     

Activated T lymphocytes resist the toxic effects of the adenosine deaminase inhibitor, 2-deoxycoformycin

Tonsil lymphocytes from three adults and three children were examined for immunoglobulin (Ig) production before and after Epstein-Barr virus (EBV) transformation. T-cell depletion was required to obtain cell lines from EBV-seropositive individuals. Cytoplasmic Ig was mainly IgG in adult lymphocytes before and after transformation; IgA and IgM were more prominent after than before. IgM and IgG predominated in lymphocytes of children before and after transformation; IgA was more prominent after than before. Cytoplasmic Ig of peripheral blood lymphocytes from these individuals was mainly IgM. Secreted Ig from tonsil lymphocytes was mainly IgA or IgG; after transformation IgM predominated with adult cell lines, and IgG or IgM with cell lines from children. IgE was consistently sparse in spite of ragweed and/or grass allergies of the adults.     

Polyclonal immunoglobulin response of thymic,hepatic and splenic lymphocytes from fetal,germ-free and conventionally reared pigs to different B-cell activators

Immunoglobulin (Ig) response to different polyclonal B-cell activators was measured by ELISA in cell culture media of thymocytes, splenocytes and liver cells isolated from pig fetuses, 8-d-old germ-free piglets and conventionally reared pigs. Both in fetal and in postnatal life polyclonally stimulated lymphocytes were found to produce predominantly the IgM isotype; the first IgM formation was detected in 50-d-old fetal liver (gestation in pigs lasts 114 d). Surprisingly, 73-d-old fetal thymic cells were shown to be induced to Ig synthesis and secretion. In contrast to splenocytes of the same age, which secreted exclusively IgM, fetal thymocytes produced IgM, IgG and IgA. Polyclonally stimulated splenic cells as compared with thymic cells started to produce IgA later in fetal ontogeny, whereas the IgG response was not detectable in splenic cell culture media during the whole embryonal development and appeared only after birth. The earliest and the highest Ig stimulation was found after cultivation of lymphocytes withNocardia delipidated cell mitogen. Interestingly, the moderate stimulatory effect of 65-kDa heat shock protein (Hsp-65) in polyclonal IgM response of fetal splenocytes was observed. We showed that thymic B lymphocytes represent probably the first maturing B cell population detectable in fetal life, which is able to differentiate after polyclonal stimulation into IgM as well as IgA and IgG producing cells. Dedicated to Professor J. Šterzl on the occasion of his 70th birthday     

Immune reconstitution in the immunodeficient chicken by transfer of embryonic lymphoid cells

Embryonic chickens were rendered immunodeficient by in ovo injection of homologous IgM on the 10th embryonic day. The immunodeficient embryos were intravenously given lymphoid cells taken from normal embryonic bursa, spleen or thymus on the 15th embryonic day. Gain of splenic or bursal weight, natural antibodies to sheep red blood cells (SRBC), frequencies of rosette forming cells (RFC) binding to SRBC or dinitrophenyl-SRBC (DNP-SRBC) and of immunoglobulin bearing cells (IBC) in the bursa and the spleen were investigated to assess the effect of transferred cells during the embryonic stage. Transferred bursal and splenic cells showed an ability to restore the frequency of RFC or IBC in the recipients. However, reversion from the immunodeficient state was not observed in the thymic cell transfer. These findings suggested that the cells derived from embryonic bursa and spleen contained stem cells which developed into RFC and also into precursors of IBC.     

Ia-like alloantigens in the chicken: Serologic characterization an ontogeny of cellular expression

Alloantisera raised in highly inbred lines of chickens, 7(2) and 15I(5) , by reciprocal immunization with lymphocytes were shown by immunofluorescence to react with B cells, cells of the monocyte-macrophage series, and an unidentified population of mononuclear cells prevalent in the spleen and bone marrow. Variable immunogenicity of the 'Ia'(2) and 'Ia'(15) alloantigens was observed. The alloantigens detected by these sara could be redistributed on the B-cell surface independently of immunoglobulin determinants or previously recognized antigens encoded by the major histocompatibility complex (B locus), and were more resistant to proteolysis than slgM. Analysis of several inbred lines of chickens revealed an association between expression of these antigens and the B haplotype. Strains of the B(2) haplotype expressed the antigen detected by anti-7 2 and vice versa. These data suggest that the B-cell alloantigens detected are encoded by genes linked to the MHC and may be analogous to la antigens of mice and DR antigens of man. 'Ia' alleles were co dominantly expressed on lymphocytes of F(1) hybrids. During ontogeny 'a'(+) cells were first detected in the bursa at 10 days of incubation , 3 days before 'Ia'(+). IgM(+) cells could be detected. Both 'Ia'(+).IgM(+) and 'Ia'(+).IgM(-) populations of bursal cells increased in parallel until day 18, when plateau levels were reached. Development of 'Ia'(+).IgM(-) cells throughout the body was unaffected by bursectomy at hatching. Cell surface expression of 'Ia' antigens was apparently increased with B-Iymphocyte maturation and was detectable on most, but not all, mature plasma cells.     

Development and distribution of B lineage cells in the domestic cat: analysis with monoclonal antibodies to cat mu-, gamma-, kappa-, and lambda-chains and heterologous anti-alpha antibodies

To trace the development and distribution of B lineage cells in the domestic cat (Felis catus), we have produced monoclonal antibodies against mu-, gamma-, kappa-, and lambda-chains of feline immunoglobulins (Ig). Goat antibodies against human mu-, alpha-, and lambda-chains, which are reactive with shared determinants on their feline counterparts, were used in conjunction with the panel of mouse monoclonal antibodies. Cytoplasmic mu+ pre-B cells and surface IgM+ B lymphocytes were observed in 42 day fetal liver in which pre-B cells were more abundant than IgM+ B cells. Pre-B cells also were found in bone marrow in young cats, and continued to be generated in the marrow throughout life. In the spleen, adult levels of B cells were attained by 12 wk of age, at which time the frequencies of surface IgM+, IgG+, and lambda+ cells were 49, 3, and 40%, respectively. The distributions of Ig isotypes also were determined among plasma cells as a function of age and tissue localization. IgM plasma cells were predominant in the bone marrow of 1-wk-old cats, whereas IgG plasma cells were the prevalent isotype in adult bone marrow. In the mesenteric lymph nodes of adult animals, the frequency distributions of IgM, IgG, and IgA plasma cells were similar to the frequency distributions of IgM, IgG, and IgA isotypes among bone marrow plasma cells. IgA+ plasma cells predominated in the intestinal lamina propria, in which IgG+ and IgM+ plasma cells were relatively infrequent. In the tissues of both young and adult animals, the ratio of lambda:kappa expression was approximately 3:1. We conclude that the pattern of B cell development in the cat resembles that found in other mammals, except that the kappa to lambda ratio is reversed.     

IgM complex receptors on subpopulations of murine lymphocytes.

Murine lymphocytes from spleen, lymph node, and thymus were examined for IgM complex receptors. Lymphocytes from all three organs were found to bind SRBC sensitized with IgM from various sources including: primary anti-SRBC serum, murine and rabbit anti-Escherichia coli LPS sera, and a murine IgM myeloma (MOPC 104E). Rosette formation by lymphocytes with IgM-sensitized SRBC was inhibited by soluble antigen-IgM complexes but not by IgM or antigen alone. Rosette formation was also inhibited by human IgM (Fc)5mu but not by Fab mu. Antiserum and complement treatment of the cells and subsequent recovery of the viable cells by trypsinization, filtration, and washing revealed the IgM rosette-forming cell (RFC) in the thymus to be a T cell. Spleen on the other hand was found to contain both B and T cells capable of binding IgM sensitized SRBC. Removal of both B and T cells from spleen cell suspensions eliminated all IgM RFC. The IgM complex receptor was found to be trypsin insensitive. Anti-Ig column fractionation enriched IgM RFC in spleen and lymph node suspensions passed through the columns, whereas cells bearing surface Ig, IgG complex receptors, and C3 receptors were retained in the columns.     

Ontogeny of immunoglobulin expression in the Mexican axolotl

The ontogeny of immunoglobulin (Ig) synthesis was followed at both cellular and serological levels in the Mexican axolotl (Ambystoma mexicanum) using polyclonal antibodies recognizing all Ig molecules and a set of monoclonal antibodies (Mabs) specific for the C mu and Cv heavy Ig chain isotypes and for the light chain constituents shared by IgM and IgY molecules. Clusters of IgM- and of IgY-synthesizing lymphocytes, often located in separate sites, are first present in spleen sections of 7-week-old 25 mm larvae, about one month after differentiation of the spleen anlage (stage 39-40). In 12-week-old 30-35 mm larvae, the relative proportion of IgM- and IgY-synthesizing cells in the spleen is the same as that in adult animals. However, a marked enhancement of the spleen B cell compartment occurs from 5 to 9 months when Ig-positive cells represent about 88% of the lymphocytes population compared to 60% in adults. No structures equivalent to B cell germinal centers were observed at any stage of the spleen differentiation and cells, although often clustered in small groups, remain dispersed in the entire organ. The relative proportions of IgM and IgY B cells throughout the spleen remain constant during development (about 1 IgY+ cell for 5-6 IgM+ cells) and IgM molecules are first detected in the serum of 2.5-month-old larvae. The enhancement of the serum IgM level correlates well with the absolute number of IgM+ cells in the growing spleen. IgY molecules cannot be detected in the serum before the 7th month but their level quickly increases to reach about 60% of the adult value at 10 months. Thyroxine-induced metamorphosis or hyperimmunization of 4- to 6-month-old larvae had no effect upon the temporal expression of the Ig classes in serum.     

Migratory patterns of B lymphocytes: II. Fate of cells from central lymphoid organs in the chicken

Studies were made of the fate of ³H-nucleoside-labeled chicken bursa, thymus and bone marrow cells after intravenous injection into 8-day-old, irradiated chickens. A higher rate of proliferation of bursa cells was indicated by the fact that bursa cells incorporated more ³H-thymidine and ³H-adenosine than thymus cells, while ³H-uridine incorporation was similar for these two cell types. Homing patterns in recipient spleen tissue were similar for all three nucleoside-labeled bursa cells. Bursa cells localized in follicular and periellipsoidal areas, whereas thymus cells preferentially homed to periarteriolar sheaths. Bone marrow cells were found in all these locations. Bursa cells from chickens aged 4 weeks and older showed a greater tendency to home to the spleen than did bursa cells from 8-day-old donor chickens. Homing to other tissues appeared independent of donor age.     

Ontogeny of lymphoid organs and development of IgM-bearing cells in Atlantic halibut (Hippoglossus hippoglossus L.)

In teleost fish, the head kidney, thymus, and spleen are generally regarded as important immune organs. In this study, the ontogeny of these organs was studied in Atlantic halibut (Hippoglossus hippoglossus), larvae at various stages of development. We observed that the kidney was present at hatching, the thymus at 33 days post hatch (dph), while the spleen was the last organ to be detected at 49 dph. All three lymphoid organs were morphologically well developed during late metamorphic stages. Real time RT-PCR analysis showed that IgM mRNA expression could be observed at 66 dph and later, which correlates well with in situ hybridisation data showing that a few IgM positive cells could be detected in the anterior kidney and spleen from 66 dph. Our data also showed that the highest levels of IgM mRNA could be detected in halibut spleen. Immunostaining using a monoclonal antibody against halibut IgM detected IgM positive cells at 94 dph in both the head kidney and the spleen, which is much later than the IgM mRNA. Numerous cells expressing both IgM mRNA and protein could be detected in the spleen and anterior kidney and also to some extent in thymus specimens from adult halibut.     

鸡新城疫副眼和副鼻器官微环境局部免疫机理的研究——Ⅰ.血清学和免疫荧光研究

本文研究了用新城疫B_1系疫苗免疫后的SPF雏鸡的泪液、唾液,气管粘液和血液中的血凝抑制(HI)抗体的性质和动态变化规律;同时采取哈德泪腺、气管、肺脏、脾脏、胸腺和法氏囊,作低温组织切片间接免疫荧光试验。结果证明:泪液、唾液和气管粘液中存在着HI抗体.经过两次免疫后,这种抗体至少可持续71天,而且在免疫初期(泪液在一免后的第26天前,唾液和气管粘液在一免后的第29天前)这些外分泌液中的HI抗体滴度要比血液中相应的抗体滴度高.说明这些抗体主要是由局部免疫组织产生的,而不是由血液中机械性渗透来的。哈德泪腺是以B淋巴细胞为主的外周免疫器官,它是在局部产生抗体的主要部位,同时气管、肺脏的局部淋巴组织也参与抗体的合成。参与局部免疫的抗体主要属于IgA。局部免疫反应以体液免疫为主,并由体液免疫和细胞免疫共同完成。     

Detection and quantification of IgM(+) lymphocytes in fetal lamb spleen, liver and lymph nodes by flow cytometry

The first stage in Peyer's patch development in the fetal lamb is characterized by the colonization of the rudimentary Peyer's patches by precursor cells expressing the IgM surface receptor. In the fetal lamb, the spleen has been implicated as the source of gene-rearranged IgM(+) B lymphocytes. This study was intended to quantitate IgM(+) lymphocytes in the spleen, lymph nodes and liver of fetal lambs at various gestational ages between 63 and 110 days using flow cytometry. Flow-cytometric analysis revealed that IgM(+) lymphocytes were rare in the liver being consistently less than 1% at every gestational age examined. IgM(+) lymphocytes were detected in the spleen (mean 9.18%) and prescapular lymph nodes (mean 11.89%) as early as 63 days. In both spleen and lymph nodes, the highest representation of IgM(+) lymphocytes occurred between 70 and 86 days gestation. The highest mean percentage of IgM(+) lymphocytes was observed in the spleen (22.63%) and lymph nodes (17.02%) at 75 days gestation. From 98 days onwards, B-lymphocyte density gradually decreased in both spleen and prescapular lymph nodes. This study indicates that substantial populations of IgM(+) lymphocytes were present in both the spleen and prescapular lymph nodes from 70 days gestation and implies that both of these locations could be potential sources for the normal colonization of the ileal Peyer's patches.