tending to react to a stimulus

Lymphoid tissue is the functional tissue of reactive lymphoid organs. Reactive lymphoid organs provide immune surveillance of body cavities connected to microbe-containing environments or provide surveillance of body fluids.




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Note added at 10 hrs 18 mins (2004-12-24 04:24:25 GMT)
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The functional tissue in secondary or reactive lymphoid organs consists of lymphocytes and other immune system


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Note added at 10 hrs 48 mins (2004-12-24 04:55:06 GMT)
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Stimulants are proper antigen, microorganisms etc

http://www.geocities.com/artnscience/peripheral-lt.html

Reactive lymphoid tissue is lymphoid tissue after antigenic stimulation (i.e. after the influence of an antigen). Reactive lymphoid tissue contains the germinal centers (çàðîäûøåâûå öåíòðû, in Russian) which are believed to generate the B-cells.

In case you need English synonyms, then reactive lymphoid tissue = antigenically stimulated lymphoid tissue. Pls note that reactive lymphoid tissue may be both normal or neoplasmic.



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In reactive lymphoid tissue, during a B-cell-dependent
immune response, follicular centres are formed by mature naive B-cells
derived from the extrafollicle. FCs have roles in clonal
expansion and antigen-driven proliferation of B-cells,
somatic hypermutation of immunoglobulin (Ig) genes, and
generation of memory B or plasma cells.
http://147.52.72.117/IJO/2002/volume21/number5/957-963.pdf

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.. lymphocytes may be cytologically indistinguishable from normal resting lymphocytes or antigenically stimulated lymphocytes in reactive lymphoid tissue. ...
arjournals.annualreviews.org/ doi/abs/10.1146/annurev.me.39.020188.001531

The answer was provided by one of the colleagues, but it has been hidden between the words in the explanation. I have found this definition of lymphoid tissue also (the functional part of the organ).
I did some research in Russian and I am sure that the only meaning of "reactive lymphoid tissue" is " active" (biologically active, functional)esp.in the first sentence. There are some articles with both of the terms together (functional active or via versa) and it is really common immunology expression.

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Note added at 4 days (2004-12-28 07:11:54 GMT)
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On the second thought I guess that this term has the different meanings in this small abstract. The first case [in ***reactive lymphoid tissue*** (e.g. lymph nodes, and lymphoid tissues of the alimentary and respiratory tracts and spleen)]provides a description of the tissue\'s location and the synonym can be \"secondary\".
http://ntri.tamuk.edu/immunology/cells.html
*The primary lymphatic organs are the bone marrow and thymus, where immature lymphocytes differentiate into antigen-sensitive B cells and T cells. The secondary lymphatic organs are the spleen, lymph nodes, adenoids, tonsils, peyer\'s patches and appendix. All secondary lymphoid organs serve as sites where B and T cells may encounter antigen. This will stimulate proliferation and differentiation of the B and T Cell.*
http://www.cvm.okstate.edu/instruction/mm_curr/histology/His...
* Immature T lymphocytes move from the bone marrow into the thymus, take up residence and become thymus-dependent or mature T lymphocytes. These mature T cells then pass through the circulation to find homes in lymph nodes, mucosa-associated lymphoid tissue or the spleen. There are several types of T lymphocytes, i.e., T helper cells, cytotoxic T cells and suppressor T cells. B lymphocytes originate and mature in the bone marrow then move through the circulation to various sites throughout the body. Upon interaction with foreign antigen and usually with the assistance of T helper cells, B lymphocytes become mature antibody secreting cells called plasma cells. Clones of plasma cells making specific immunoglobulins are produced thus providing the large numbers of plasma cells needed to mount a good antibody (humoral immune) response. Plasma cells are rarely found in the circulation but reside mostly in connective tissue (lamina propria) beneath epithelia, in the medullary cords of lymph nodes and in the white pulp of the spleen.
So, they only *may encounter antigen. This will stimulate proliferation and differentiation of the B and T Cell.* And this location is *one of the first lines of defense against invading microorganisms, viruses and parasites.In these types of locations, they are perfectly positioned to interact with invading foreign substances and they recognize these substances as non-self or foreign. Upon such \"recognition\" lymphocytes are activated and function to neutralize or destroy the invading foreign substance.*
The 2-nd and the 3-d cases are different. The author does not mean now the normal location from the anatomy but the difference between *reactive and neoplastic lymphoid cells*.
There are at least two types of these cells when they would appear. The first type can be 1/ inmature blood cells, they can be found in the peripheral blood right after the effective blood losses(their appearance is not normal, of course, but it is a good sign of the bone narrow reaction);2/the increase of a number (eg,erythrocytosis under some conditions). I guess that the synonym would be \"compensatory\".
http://www.fibrogen.com/rd/hif/
A key protein called hypoxia-inducible factor (HIF) coordinates the several compensatory changes that comprise the hypoxic response, and enzymes called prolyl hydroxylases (PH) regulate the stability and activity of HIF.
http://www.vmeda.ru/centr/ResearchCentre.htm
structural and functional changes in cell structures under pathological, compensatory and regenerative processes in different diseases and traumas.

The second type is the appearance of *reactive leucocytosis ,reactive lymphocytosis, reactive thrombocytosis*,etc. Sometimes these changes are called also \"secondary\" but the meaning is that they appear as a response for something \"primary\"(conditions,infection,etc.). So, I am not sure how to name the synonym in this case but it is supposed to be something \"between normal state and pathology\", may be
\"BENIGN\" vs malignant.
*The alterations
could occur as a result of inflammation, metaplasia, re-growth, radiation, or defects in normal, nonneoplastic
maturation. Often, the cause of reactive change remains obscure to the pathologist’s eye.
Reactive changes may be observed in either glandular or squamous epithelium.In Papanicolaou smear interpretation, the term “reactive epithelial changes” is often a sign of
benign cellular alterations which exceed the appearances of normal epithelium. Reactive changes
can be misinterpreted as neoplastic.*
http://www.asheducationbook.org/cgi/content/full/2000/1/180
Analysis of lymphoid clonality is frequently useful in the distinction of malignant vs. reactive lymphadenopathy in cases for which morphological and immunological analysis is inconclusive. Detection of apparently clonal proliferations in clinically benign conditions such as large granular lymphocytosis, lymphomatoid papulosis or Sjögren\'s syndrome illustrate, however, that clonality is not synonymous with malignancy,16, 17 and it is increasingly clear that dys/autoimmune disorders represent one end of the spectrum of lymphoproliferative disorders. http://ajp.amjpathol.org/cgi/content/full/162/3/861
In reactive lymphoid tissue (eg, cases of dermatopathic lymphadenitis and infectious mononucleosis), OCT-2 expression was essentially restricted to B cells, only scattered CD2-positive and exceptional CD4-positive T-lymphocytes being stained. Accordingly, the majority of T-cell neoplasms did not carry OCT-2, the exception being some peripheral T-cell lymphomas (NOS) and ALK-positive lymphomas, of which 50% were OCT-2-positive. Notably, ALK-negative lymphomas with anaplastic large cell morphology were all OCT-2-negative. The significance of OCT-2 immunostaining in T-cell lymphomas is unknown but it may conceivably relate to reports that OCT-2 can be expressed in T cells after in vitro activation.

http://www.lf2.cuni.cz/info2lf/ustavy/upa/eng/otazky.htm
White blood cell disorders:
a)reactive conditions :leucocytosis, leukopenia,infectious mononucleosis;
b)leukemias and myeloproliferative diseases,classsification:
1.acute leukemias (ALL, AML);2.myelodysplastic syndromes.