| Objective:：To investigate the variation of immune function under differentambient temperatures by observing the rat splenic pathological changes and thechanges in the number of lymphocytes when the ambient temperature has a suddenchange alone and with LPS/Con A stimulation, and thereby to provide a theoreticalbasis for disease prevention and treatment under extreme weather.Methods：According to different temperatures and whether LPS/Con Astimulation was given, one hundred and forty-four male SD rats (9-15weeks old)were randomly divided into12groups (12rats per group): normal temperature (20℃),normal temperature plus LPS stimulation, normal temperature plus Con A stimulation,4℃low temperature,4℃plus LPS stimulation,4℃plus Con A stimulation,﹣12℃low temperature,﹣12℃plus LPS stimulation,﹣12℃plus Con A stimulation,37℃high temperature,37℃plus LPS stimulation and37℃plus Con A stimulation.Four observing time points (1h,8h,24h and168h;3rats per time point) were set foreach group. Following a7-day control period at normal temperature (20℃), theanimals were treated with different temperatures and intraperitoneal injections of LPS(1mg/kg)/Con A (5mg/kg), respectively. The animals were sacrificed at their settime points, respectively, to take the spleen tissue. The taken tissue was fixed in4%paraformaldehyde solution, paraffin-embedded and sliced for routine HE staining andimmunohistochemical assays of CD3~+T cells, CD8~+T cells and CD20~+B cells.Stereological measurements were performed to calculate the number densities of thethree types of cells. The software SPSS statistics17.0was employed for comparisonsof the differences within various temperature groups for each parameter and thedifferences between various temperature groups and when combined with LPS/ConA stimulation.Results：1. Varying degrees of pathological changes occurred in the rat spleen inthe groups of temperature stimulation alone (4℃control group,﹣12℃control groupand37℃control group), mainly manifested as atrophied splenic white pulp, reducedsplenic lymphoid nodules, and decreased cell number and density and sparse cell distribution in the periarterial lymphoid sheath and lymph nodules, which were mostserious in the﹣12℃group. When compared with the normal control group, thinnersplenic periarterial lymphatic sheath appeared in the groups of LPS/Con Astimulation alone; increased lymphoid nodules and clear germinal centers rich in cellsappeared in the group of LPS stimulation alone; reduced lymphoid nodules and cellnumber appeared in the group of Con A stimulation alone. When the temperaturechanged in combination with LPS stimulation, germinal centers were frequently seenbut fewer than when temperature changed alone, and the periarterial lymphaticsheaths were significantly thinner, the cell density in which was sparse. Whentemperature changed in combination with Con A stimulation, the periarteriallymphatic sheaths were slightly thinner and the cell density in lymphoid nodules wassparse.2. In the normal temperature control group, the cells within periarteriallymphatic sheaths were mainly CD3~+and CD8~+T cells and the cells within lymphoidnodules were mainly CD20~+B cells in the rat spleen. These cell types were scatteredwithin the marginal zone and red pulp.3. Compared with the normal temperature control group, the number densities ofCD3~+and CD8~+T lymphocytes were lower in the groups of temperature stimulationalone, whereas those of CD20~+B cells were higher.4. Compared with the normal control group, the number densities of CD3~+andCD8~+T cells were lower in the groups of LPS/Con A stimulation alone, while thoseof CD20~+B cells were higher.5. The number densities of CD3~+, CD8~+T lymphocytes in the temperaturechange~+LPS/Con A stimulation groups were lower than those in the normaltemperature~+LPS/Con A stimulation groups, while those of CD20~+B cells werehigher.6. The effects of different temperatures on lymphocytes differed in varyingdegrees. CD3~+and CD8~+T cells decreased due to high or low temperature, with theimpact of low temperature more significant. CD20~+B cells increased due to high orlow temperature, with the impact most significant in the4℃group.Conclusions：1. Both a sudden drop and a sudden elevation in ambient temperature can result in pathological changes in the spleen: thinner periarteriallymphatic sheaths, reduced germinal centers, and reduced lymphoid nodules.2. Both a sudden drop and a sudden elevation in ambient temperature can lead tochanges in the number of spleen lymphocytes, including cell-mediated immunitysuppression such as a reduction of CD3~+and CD8~+T cells and enhanced humoralimmunity such as an increase of CD20~+B cells.3. When the ambient temperature has a change in combination with LPS/Con Astimulation, a further reduction in the number densities of CD3~+and CD8~+T cellsand a further increase in the number density of CD20~+B cells in spleen tissueappears, that is, the cell-mediated immunity is further suppressed and the humoralimmunity is further enhanced. Con A has a stronger inhibitory effect on cell-mediatedimmunity while LPS has a stronger promotive effect on humoral immunity. |
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