Activated T lymphocytes differentiate into effector cells tailored to meet disparate challenges to host integrity. For example, type 1 and type 2 helper (T(H)1 and T(H)2) cells secrete cytokines that enhance cell-mediated and humoral immunity, respectively. The chemokine monocyte chemoattractant protein-1 (MCP-1) can stimulate interleukin-4 production and its overexpression is associated with defects in cell-mediated immunity, indicating that it might be involved in T(H)2 polarization. Here we show that MCP-1-deficient mice are unable to mount T(H)2 responses. Lymph node cells from immunized MCP-1(-/-) mice synthesize extremely low levels of interleukin-4, interleukin-5 and interleukin-10, but normal amounts of interferon-gamma and interleukin-2. Consequently, these mice do not accomplish the immunoglobulin subclass switch that is characteristic of T(H)2 responses and are resistant to Leishmania major. These effects are direct rather than due to abnormal cell migration, because the trafficking of naive T cells is undisturbed in MCP-1(-/-) mice despite the presence of MCP-1-expressing cells in secondary lymphoid organs of wild-type mice. Thus, MCP-1 influences both innate immunity, through effects on monocytes, and adaptive immunity, through control of T helper cell polarization.
Summary. The DNA content of sperm, spermatide, and brain cell nuclei was determined by Feulgen microspectrophotometry in Dysdercus intermedius. Both in haploid and diploid cells 2 classes of DNA content were found. The differences are due to a large X chromosome in this male XO type bug. The absolute amounts of DNA represented by the X chromosome and the complete genome were calculated.Sex determination of the XO type was discovered in a bu~g in 1890 by Henking 2 and later described in several insects ~. In Lepidoptera the female is the ZO type; in Orthoptera, Hemiptera and Heteroptera the male is the XO typed heterogametic sex 4. It is assumed that such karyotypes evolved from XY ancestors by translocation or Robertsonian fusion of the Y chromosome 5. In Drosophila the small heterochromatic Y chromosome carries only a few genes concerned with male fertility 6. The transcriptional activity is restricted to spermatogenesis 7'8. On the other hand, many genes are located in the large X chromosome including loci for sex determination and oogenesis 9. The X chromosome contributes 18% of the haploid genome DNA in Drosophi- cus intermedius, and calculated the X chromosome value in this male XO type insect.Material and methods. Sperm, spermatides, and brain cells were isolated from adult bugs of the laboratory strain. The cells were lysed in 0.5% Triton X 100 solution to which 200 mg/1 spermidine phosphate (Sigma, Miinchen) had been added to stabilize the nuclear membranes. The nuclear preparations were air-dried on chromalum-coated slides and postfixed in ethanol/acetic acid 3 : 1 for 30 min. Hydrolysis was performed in 5 N HC1 for 40 min at 21 + 1 ~ The Feulgen reaction and microspectrophotometric DNA determination at 560 nm wavelength using a Zeiss UMSP II 9 12were done as routine techniques . For each type of nucleus two or more bugs were used; 2 slides were made from each bug. Each nucleus was measured 3-4 times and the average extinction was calculated. The data were processed on a Zeiss Kontron IBAS I system.
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