板蓝根多糖对缺乳仔鼠免疫器官发育及T淋巴细胞亚群的影响

试验应用流式细胞术检测缺乳仔鼠CD3⁺、CD4⁺和CD8⁺ T淋巴细胞含量来研究添加不同剂量的板蓝根多糖(RIP)对缺乳仔鼠免疫器官及T淋巴细胞亚群的影响。结果表明:①RIP可增加缺乳仔鼠胸腺指数和脾脏指数。对胸腺指数和脾脏指数效果最好的RIP剂量随日龄增大而减小。②RIP可以增加缺乳仔鼠外周血CD3⁺、 CD4⁺ 、CD8⁺ T淋巴细胞数量。7~28日龄时初乳组(A组)、缺乳+中RIP组(C组)和缺乳+高RIP组(D组)3组CD3⁺ T淋巴细胞含量与缺乳组(B组)相比差异显著(P<0.05)。7~21日龄时初乳组(A组)、缺乳+中RIP组(C组)和缺乳+高RIP组(D组)3组CD4⁺ T淋巴细胞含量与缺乳组(B组)相比差异显著(P<0.05)。各处理组CD3⁺、 CD4⁺、CD8⁺ T淋巴细胞含量及CD4⁺/CD8⁺比值随着日龄的增加有所下降。适宜剂量的RIP可促进缺乳仔鼠免疫器官发育,提高T淋巴细胞亚群的水平。     

Ontogeny of T cells in the pig fetus

Mononuclear cells isolated from thymus, spleen and cord blood of pig fetuses ranging in age from 48 to 112 days were examined for the presence of sheep red blood cell rosette-forming cells (SRBC-RFC). After an initial increase from 77 % (mean) at 48 days of gestation to 88 % at 60 days, the proportion of SRBC-RFC in thymus remained constant throughout the gestational period. In spleen and cord blood, the proportion of SRBC-RFC increased with age, from occasional rosette-forming cells at 48 days of gestation to 21 % and 30 %, respectively, at 112 days. The demonstrated development of SRBC-RFC in the thymus, spleen and cord blood is considered to reflect the ontogeny of T cells in these fetal pig tissues.     

Canine X-linked severe combined immunodeficiency.

Canine X-linked severe combined immunodeficiency (XSCID) is due to mutations in the common gamma (gamma c) subunit of the IL-2, IL-4, IL-7, IL-9 and IL-15 receptors. The most striking clinical feature is a failure to thrive or 'stunted' growth. Recurrent or chronic infections begin at the time of decline of maternal antibody, usually between six and eight weeks of age. Affected dogs rarely survive past three to four months of age. The major pathologic feature of canine XSCID is a small, dysplastic thymus. Grossly identifiable lymph nodes, tonsils, and Peyer's patches are absent in XSCID dogs. During the neonatal period, XSCID dogs have few, if any, peripheral T cells and increased number of peripheral B cells. Some XSCID dogs do develop phenotypically mature, nonfunctional T cells with age, however, the absolute number of peripheral T cells remain significantly decreased compared to age-matched normal dogs. An interesting finding is that as soon as T cells begin to appear in XSCID dogs they rapidly switch from a CD45RA+ (naive) phenotype to a CD45RA- (activated or memory phenotype). One of the characteristic findings in XSCID dogs is an absent or markedly depressed blastogenic response of T cells in response to stimulation through the T cell receptor and when the necessary second messengers for cellular proliferation are directly provided that by-pass signals delivered through ligand-receptor interaction. The proliferative defect is due to the inability of T cells to express a functional IL-2 receptor. Canine XSCID B cells do not proliferate following stimulation with T cell-dependent B cell mitogens, however, they proliferate normally in response to T cell-independent B cell mitogens. Canine XSCID B cells are capable of producing IgM but are incapable of class-switching to IgG antibody production following immunization with the T cell-dependent neoantigen, bacteriophage phiX174. The number of thymocytes in the XSCID thymus is approximately 0.3% of the thymocytes present in the thymus of age-matched normal dogs. The proportion of CD4-CD8- thymocytes in XSCID dogs is increased 3.5-fold and the CD4+CD8+ population is decreased 2.3-fold. These findings demonstrate that (1) a functional gamma c is required for normal B and T cell function, (2) early T cell development is highly dependent upon a functional gamma c, and (3) B cell development can occur through a gamma c-independent pathway.     

Plasma concentrations of luteinising hormone, follicle stimulating hormone, androgen, growth hormone, prolactin, thyroxine and triiodothyronine during growth and sexual development in the cockerel

Changes in concentrations of plasma luteinising hormone (LH), follicle stimulating hormone (FSH), androgen, growth hormone (GH), prolactin (Prl), thyroxine (T4) and triiodothyronine (T3) were measured during growth and sexual maturation in broiler cockerels reared in continuous light to 7 weeks and 14 h light/d thereafter. Concentrations of LH and FSH began to increase between 13 and 15 weeks, while those of androgens increased between 16 and 17 weeks. FSH concentration increased faster than that of LH. Concentrations of GH and Prl were high at 3 weeks; that of GH decreasing progressively between 3 and 14 weeks of age and thereafter remaining low, while that of Prl was low between 5 and 9 weeks, relatively high between 10 and 13 weeks, and then temporarily decreasing before increasing progressively during sexual maturation. Concentrations of T3 and T4 were higher in juvenile than in adult birds.     

Effect of thymus extract on immunologic reactivity of chicken vaccinated with infectious bursal disease virus.

The effects of crude thymus extract on the immune response and protection against challenge with virulent infectious bursal disease virus (IBDV) were studied in one-day-old chick. Oral administration of thymus extract (1 ml/kg) markedly and significantly increased the total protein, albumin, globulin, Tri-iodothyronine (T3), Thyroxine (T4) and the body weight gain in one-day-old chick. In addition, it increased the total lymphocytic count over four weeks after administration. Although vaccination also increased total protein, globulin, T4 and the total lymphocytic count but it significantly decreased the body weight gain of the chick and administration of thymus extract, before, during or after vaccination markedly improved the vaccination effectiveness with significant elevation of the globulin level and body weight gain of the chick. It also prevented the decrease in the relative weights of bursa, spleen and thyroid gland which commonly prevailed during vaccination. Chicken administered thymus extract and vaccinated with infectious bursal disease (IBD) vaccine showed 100% protection against challenge with IBDV. Meanwhile the vaccinated non-thymus treated group exhibited 80% protection against IBDV challenge. These results indicate a potentiating effect of thymus extract on the immune system in baby chick. These findings are supported by ELISA results that showed a marked increase in antibody titers in thymus treated groups. Additionally, microscopical examination of the bursa and the existent lymphoid hyperplasia in thymus treated groups but not vaccinated group support our findings.     

Changes in serum thyroid hormone levels in newborn calves as a diagnostic index of endemic goiter

Maximum serum thyroxine (T4) and triiodothyronine (T3) levels of healthy calves were seen at 1 day after birth, and thereafter rapidly decreased until 5 days after birth. They stabilized until 2 weeks after birth, then gradually decreased until 4 weeks after birth. Serum T4 levels of calves with endemic goiter tended to be lower than those of healthy ones, but showed similar levels to those of adult cows. T3 levels of calves with goiter were similar to those of healthy ones, but showed higher variation. T4/T3 ratio of calves with goiter were significantly lower than those of healthy ones and adult cows. While individual levels of serum T4 and T3 at just after birth could not be considered as a diagnostic index, the T4/T3 ratio could be adopted as a diagnostic index of endemic goiter.     

鸡贫血因子病全身免疫功能变化的研究

用鸡贫血病毒（ＣＡＶ）感染１日龄ＡＡ雏鸡,以未感染同龄ＡＡ雏鸡为对照,感染后不同时间检测其外周血液Ｔ、Ｂ细胞数量和ＩｇＧ,ＩｇＭ,ＩｇＡ含量,胸腺,法氏囊,脾脏ＩｇＧ,ＩｇＭ,ＩｇＡ抗体生成细胞和Ｔ细胞数量以及Ｔ、Ｂ细胞增殖功能;胸腺和脾脏白细胞介素２（ＩＬ－２）和干扰素（ＩＦＮ）诱生活性等的动态变化。     

H9亚型禽流感油乳剂灭活苗免疫产生期内T淋巴细胞表型亚类的检测与研究

采用免疫荧光法、使用流式细胞检测仪对经H9亚型禽流感病毒人工感染SPF鸡、H9亚型禽流感油乳剂灭活苗免疫SPF鸡以及经免疫后使用H9亚型禽流感病毒攻毒后的SPF鸡外周血、脾脏、胸腺中T细胞表型亚类(CD4+、CD8+、TCR1+)的变化规律进行了监测,结果表明,H9亚型禽流感油乳剂灭活苗免疫后抗原的缓慢释放可在一定程度上激发机体的细胞免疫应答,使免疫活性T淋巴细胞得到活化,免疫后鸡体外周血中CD4+、CD8+和TCR1+T细胞的数量呈现出一明显升高的过程;同时,人工感染免疫鸡后,脾脏和胸腺TCR1+T细胞的数量上升,外周血CD4+、CD8+和TCR1+T细胞的数量少量降低或维持不变,随后短期即恢复正常;而人工感染SPF对照鸡后,外周血CD4+、CD8+和TCR1+T细胞的数量呈现下降趋势.     

Expression of Toll-like receptor 9 (TLR9) in the lungs and lymphoid tissue of pigs

The pattern of distribution of Toll-like receptor 9 (TLR9) in different tissues varies between species. The aim of the present study was to describe the distribution of TLR9 expression in selected tissues and organs of healthy pigs at 3 weeks and 3 months of age. Representative formalin-fixed samples of lung, thymus and secondary lymphoid tissues were evaluated by immunohistochemistry. TLR9 positive staining was observed in epithelial cells, vascular endothelium and myoepithelial-like cells, as well as in cells of the alveolar septa of the lung. Antigen presenting cells of perifollicular zones (interdigitating, macrophage and dendritic-like cells) of the Peyer's patches, lymph nodes, spleen and thymus were also immunoreactive for TLR9. No differences were seen in TLR9 protein expression in tissues from the two age groups.     

刺五加多糖对雏鸡脾脏中T、B淋巴细胞定位分布的影响

为了研究雏鸡注射不同浓度刺五加多糖(ASPS)后脾脏中T、B淋巴细胞定位分布的变化情况,将60只1日龄雏鸡随机分为3组:对照组、低剂量组和高剂量组,每组20只,10日龄起对低、高剂量组雏鸡分别皮下注射免疫50和200 mg/m L的ASPS 0.2 m L,对照组雏鸡以相同方式注射等体积的生理盐水,连续注射4 d。于末次免疫后第7天和第14天,从每组中分别随机选取5只雏鸡,取其脾脏制作冰冻切片,采用免疫组织化学方法检测CD3+T淋巴细胞和Bu-1+B淋巴细胞的定位分布。结果显示,与对照组比较,低、高剂量组在注射后的7 d和14 d ASPS均能增加脾脏中CD3+T淋巴细胞和Bu-1+B淋巴细胞的数量,由CD3+T淋巴细胞构成的脾脏特征性结构-动脉周围淋巴鞘(PALS)的面积也显著增加,红髓中CD3+T淋巴细胞也明显增多,分布范围逐渐增加;同时,由Bu-1+B淋巴细胞构成的椭球周围淋巴鞘(EALS)的面积也明显增加,红髓和白髓中的浆细胞数量显著增多,并在注射后14 d时出现生发中心。与对照组比较,高剂量组和注射后14 d时上述变化趋势更为明显。结果表明,ASPS能够增加脾脏中T、B淋巴细胞的数量,并且能够影响其在PALS、EALS等脾脏特征性结构中的定位分布,从而从组织学角度进一步证明ASPS对鸡免疫功能具有显著的增强作用。     

The critical time of avian leukosis virus subgroup J-mediated immunosuppression during early stage infection in specific pathogen-free chickens

The critical time of avian leukosis virus subgroup J (ALV-J)-mediated immunosuppression was determined by body weight, relative immune organ weight, histopathology, and presence of group specific antigen and antibodies in specific pathogen-free (SPF) chickens. CD4⁺ and CD8⁺ cell activity in the spleen, total and differential leukocyte counts in blood, and viral RNA levels in spleen were measured. Significant growth suppression was observed in the two ALV-J-infected groups. A strong immune response by infected groups was present in spleen at 2-weeks-of-age, but after 4-weeks-of-age, the response decreased quickly. The thymus and bursa showed persistent immunosuppression until 4-weeks-of-age. Proliferation of fibroblasts and dendritic cells were observed in immune organs at 4- and 5-weeks-of-age. However, the granulocyte cell number was markedly lower in the infected groups than in the control group. In group 1 (day 1 infection) CD4⁺ cells increased during the second week but significantly decreased during the fourth week, while group 2 (day 7 infection) showed the opposite effect. Viral RNA increased significantly by the fourth week. These data identify 3~4 weeks post-infection as the key time at which the ALV-J virus exerts its immunosuppressive effects on the host.     

Growth changes of the collagen content and architecture in the pectoralis and iliotibialis lateralis muscles of cockerels

1. Growth changes of the collagen content and architecture in the pectoralis (PT) and iliotibialis lateralis (ITL) muscles were examined using cockerels from 1 to 14 weeks of age. 2. Total collagen content in PT muscle showed little change, but in ITL muscle reached a maximum at 5 weeks and thereafter decreased slightly until 14 weeks. The collagen content was markedly larger in ITL muscle after 5 weeks. Pyridinoline content of collagen increased abruptly from 5 to 14 weeks in both muscles, but no difference between muscle types was detected. 3. The cell size of the endomysial honeycombs increased with the development of myofibres, and the mesh size of the perimysium around the honeycombs enlarged. 4. In both muscles endomysia were an incomplete network of collagen fibrils with many foramina at one week, became a very thin membrane of felt-like fabric in 2 to 5 weeks and thereafter increased in thickness until 11 to 14 weeks. 5. Perimysial width around the secondary fasciculus differed between the muscle types after 5 weeks. In the wider perimysium of ITL muscle, the collagen fibres increased in number and size to make a stack of collagen bands around the fasciculus. In the narrower perimysium of PT muscle, a few platelets of collagen fibres also developed. 6. The perimysial collagen fibre at 1 to 2 weeks had a smooth surface and appeared to be composed of fine collagen fibrils. The fibre at 11 to 14 weeks showed a rugged surface and was composed of coarser collagen bundles that combined with each other into a net-like configuration with very slim meshes. 7. Our results showed that the collagenous components of chicken intramuscular connective tissue changed markedly during the early period of muscle growth in distribution, architecture and quality but with little difference in quantity.     

Thioacetamide toxicity and the spleen: histological and biochemical analysis

Exposure to thioacetamide is associated with the development of liver cirrhosis in experimental animals. In addition to liver, thioacetamide toxicity has been observed in other organs. In this study, the toxic effect of thioacetamide on the spleen was investigated at 0, 4, 8 and 12 weeks post-treatment durations. The level of tissue copper and selenium increased until the eighth week when a significant drop was observed. The zinc level was also increased but returned back to normal by week 8, thereafter it showed further increase. Calculation of the copper/zinc ratio showed an increase, but, recovered and returned to normal value by week 12. The level of manganese fluctuated until the eighth week. It then increased rapidly. Histological studies of the spleen tissue showed a significant increase in extramedullary haematopoiesis in the red pulp region and marked hyperplasia in the marginal zone and follicles. The results of this study, demonstrate an intimate association between trace element levels and spleen pathology, as observed in studies of other organs.     

Influence of bestatin, an inhibitor of aminopeptidases, on T and B lymphocyte subsets in mice

Bestatin, a low-molecular weight dipeptide, is a potent inhibitor of aminopeptidase N which has been demonstrated to have antitumor and immunomodulatory effects. The effects of bestatin (10, 1 and 0.1 mg/kg) administered intraperitoneally once, five or ten times to mice on the total number of lymphocytes in the thymus, spleen and mesenteric lymph nodes and the percentage and the absolute number of T cell subsets (CD4+CD8+, CD4-CD8-, CD4+, CD8+) in the thymus and T (CD3+, CD4+, CD8+) and B (CD19+) lymphocytes in the spleen and mesenteric lymph nodes were studied. It has been found that bestatin administered ten times at doses of 10, 1 and 0.1 mg/kg increased the total number of thymocytes, splenocytes and lymphocytes of mesenteric lymph nodes. Bestatin also changed the percentage and the absolute number of T cell subsets in the thymus and T and B lymphocytes in the peripheral lymphatic organs. Five and ten exposures to bestatin (10, 1 and 0.1 mg/kg) increased the absolute count of both immature CD4+CD8+ and CD4-CD8- thymic cells. Moreover, both a single and multiple administration of bestatin (1 and 0.1 mg/kg) decreased the percentage and absolute count of CD3+ splenocytes and mesenteric lymph node cells with corresponding decreases in the percentage and absolute count of CD4+ and CD8+ cells. Both a single and multiple administration of bestatin at all the doses under investigation augmented the percentage and the absolute count of CD19+ (B lymphocytes) in the peripheral lymphatic organs. The results of the study show that there is a relationship between the effect induced by bestatin and the dose of the drug as well as the number of doses applied. The strongest effect on the T and B lymphocyte subsets was noted after five injections of bestatin at doses of 1 and 0.1 mg/kg.     

固始鸡免疫器官内T淋巴细胞亚群动态变化

应用流式细胞仪结合免疫荧光抗体技术对固始鸡和固始鸡胚胎免疫器官内T淋巴细胞亚群的动态变化和发育分化规律进行了研究.结果发现,(1)胚胎时期,胸腺内T淋巴细胞发育分化低,表现为成熟的T淋巴细胞(CD3~+)和不成熟的胸腺细胞均较少;出壳后,固始鸡胸腺内成熟T淋巴细胞增多,占胸腺细胞的30%左右,但大部分仍是未成熟的胸腺细胞.(2)脾脏内T淋巴细胞为成熟的T淋巴细胞(CD3~+),占淋巴细胞的60%左右.胚胎时期脾脏内CD3~+水平低,出壳后2周已达脾脏内正常水平(60%左右).(3)法氏囊内有少量的成熟T淋巴细胞(10%左右).结果表明,T淋巴细胞在固始鸡胸腺内增殖分化和成熟,脾脏和法氏囊内的成熟T淋巴细胞均来源于胸腺.     

Pathological and immunohistochemical studies of subclinical infection of chicken anemia virus in 4-week-old chickens

Subclinical infection of chicken anemia virus (CAV) at 4 to 6 weeks of age, after maternal antibodies have waned, is implicated in several field problems in broiler flocks. In order to understand the pathogenesis of subclinical infection with CAV, an immunopathological study of CAV-inoculated 4-week-old SPF chickens was performed. Sixty 4-week-old SPF chickens were equally divided into CAV and control groups. The CAV group was inoculated intramuscularly with the MSB1-TK5803 strain of CAV. Neither mortality nor anemia was detected in the CAV and control groups. In the CAV group, no signs were observed, except that some chickens were grossly smaller compared with the control group. Sporadic thymus lobes appeared to be reddening and atrophied. Within the first two weeks p.i. of CAV, there was a mild to moderate depletion of lymphocytes in the thymus cortex and spleen in some chickens. Moreover, lymphoid depletion of the bursa of Fabricius, proventriculus and cecal tonsils was observed. Hyperplastic lymphoid foci were observed in the liver, lungs, kidneys and heart at the 4th week p.i. of CAV. Immunohistochemically, a moderate lymphoid depletion of CD4(+)and CD8(+) T cells in the thymus cortex and spleen was observed in some chickens within two weeks p.i. of CAV. CAV inclusions and antigens were detected infrequently in the thymus cortex and spleen. It could be concluded that the immunosuppression in subclinical infection with CAV occurs as a result of reduction of cellular immunity.     

Serum Biochemical and Hematological Parameters of Captive White-tailed Fawns

Blood samples were collected, at one day of age and at weekly intervals from one through 25 weeks of age, from seven white-tailed fawns (Odocoileus virginianus) to determine the effect of age upon serum biochemical and hematological values. Serum total protein concentration increased continually during the six month period. The rate of anabolism of serum gamma-globulin exceeded the rate of catabolism at about seven weeks of age. Serum cholesterol concentration more than doubled from one day to eight weeks of age. Blood hemoglobin concentration and packed cell volume increased markedly during the first eight weeks of life, but tended to remain constant from eight to 25 weeks of age. Blood erythrocyte count increased throughout the duration of the study; however, the relative increase was greater during the first eight weeks of age than thereafter.     

传染性法氏囊病病毒超强毒感染SPF鸡免疫器官中CD4+和CD8+T淋巴细胞动态分布

利用免疫组织化学染色对传染性法氏囊病病毒（IBDV）超强毒LX株感染SPF鸡免疫器官中CD4^ 和CD8^ T淋巴细胞的动态分布进行了研究。超强毒LX株接种2周龄SPF雏鸡，在其法氏囊、脾脏、胸腺、盲肠扁桃体、骨髓和哈氏腺中均可检出IBDV抗原的存在和CD4^ 与CD8^ T淋巴细胞的数量改变。在法氏囊中，CD4^ 淋巴细胞主要存在于淋巴滤泡间隙和滤泡皮质，而CD8^ T淋巴细胞则丰在于整个淋巴滤泡和滤泡间隙，并且CD8^ T淋巴细胞数量明显多于CD4^ T淋巴细胞，在接种后14d仍未见CD4^ 和CD8^ T淋巴细胞数量减少。脾脏中CD4^ T淋巴细胞主要存在于外周小动脉淋巴鞘或散在，而CD8^ T淋巴细胞则多存在于外周小动脉淋巴鞘和红髓。接种后胸腺中CD4^ 和CD8^ T淋巴细胞在皮质中减少，但在髓质增多，尤其是CD8^ T淋巴细胞数明显多于CD4^＋T淋巴细胞。盲肠扁桃体中CD4^ 和CD8^ T淋巴细胞主要存在于发生中心，尤其是CD8^ T淋巴细胞数比CD4^ T淋巴细胞明显多。骨髓和哈氏腺中也可见CD4^ 和CD8^ T淋巴细胞，而且CD8^ T淋巴细胞更多。在这些淋巴器官中，病毒损伤部位出现CD4^ 和CD8^ T淋巴细胞的迁入聚集，表明T淋巴细胞可能参与IBDV超强毒的免疫致病过程。     

Influence of betulinic acid on lymphocyte subsets and humoral immune response in mice

Betulinic acid is a pentacyclic triterpene found in many plant species, among others, in the bark of white birch Betula alba. Betulinic acid was reported to display a wide range of biological effects, including antiviral, antiparasitic, antibacterial, anticancer and anti-inflammatory activities. The effects of betulinic acid (50, 5, 0.5 mg/kg) administered orally five times at 24 hours intervals to non-immunized and red blood cells (SRBC)-immunized mice were determined. The present study examined the total number of lymphocytes in the thymus, spleen and mesenteric lymph nodes, and the percentage of subsets of T cells (CD4+CD8+, CD4CD8, CD4+, CD8+) in thymus,T (CD3+, CD4+, CD8+) and B (CD19+) lymphocytes in the spleen and mesenteric lymph nodes, as well as white blood cell (WBC) and differential leukocyte counts in non-immunized mice, and humoral immune response in SRBC-immunized mice. SRBC was injected 24 hours after administration of the last dose of betulinic acid. It was found that betulinic acid administered orally five times at the dose of 0.5 mg/kg increased the total number of thymocytes, splenocytes, lymphocytes of mesenteric lymph node cells, and the weight ratio of the spleen and mesenteric lymph nodes in non-immunized mice. Betulinic acid also changed the percentage of T cell subsets in the thymus and T and B lymphocytes in peripheral lymphatic organs. The effects of betulinic acid on T and B cell subpopulations depended on the dose applied. The strongest stimulating effect of betulinic acid was observed when the drug was administered at the dose of 0.5 mg/kg. Five exposures to betulinic acid (0.5 mg/kg) decreased the percentage of immature CD4+CD8+ thymic cells with corresponding increases in the percentage and absolute count of mature, single-positive CD4+ thymocytes and decreased the percentage and total count of CD3+ splenocytes and mesenteric lymph node cells with corresponding decreases in the percentage and absolute count of CD4+ and CD8+ cells. Multiple administration of betulinic acid at the investigated doses augmented the percentage and absolute count of CD19+ cells in the peripheral lymphatic organs. Moreover, betulinic acid at the dose of 5 mg/kg administered prior to SRBC immunization increased the number of plaque forming cells (PFC) but decreased the production of anti-SRBC antibodies on day 4 after priming. Thus, betulinic acid is a potential biological response modifier and may strengthen the immune response of its host.     

Growth kinetics of porcine lymphatic organs during early postnatal life

During the critical early postnatal period, the development of lymphatic organs, being the major structural components of the immune system, progresses rapidly. In this context, the growth kinetics and growth rates of Peyer's patches, tonsilla veli palatini, lymphnodes (lc. mesentericum craniale and lc. bronchale), spleen and thymus were investigated in German landrace piglets from birth until 2 weeks of age. The weight of all these organs increased faster than body weight but regression analysis revealed remarkable differences in growth kinetics and growth rates. The lymphoepithelial organs (Peyer's patches, tonsilla veli palatini) had low growth rates at birth ( approximately 10%/day) that increased continuously until 2 weeks, while lymphnodes and spleen exhibited constant high growth rates ( approximately 40%/day). Small intestinal lymphnodes alone showed biphasic growth kinetics which could be attributed to colostrum absorption. The growth kinetics of the thymus included a point of inflexion at the end of the first week. The differences in growth kinetics and growth rates are discussed with regard to their immunobiological relevance.