This document provides an overview of B lymphocytes and their role in humoral immunity and periodontal disease. It discusses B cell activation, differentiation into plasma cells and memory B cells, antibody production, and the interaction of B cells and T cells. It describes how an imbalance from a Th1 to Th2 response can lead to a shift from stable to progressive periodontal lesions associated with increased antibody production and tissue destruction.

1. Dr Harshavardhan Patwal
Department of Periodontics

2. CONTENTS
1. INTRODUCTION
2. FORMATION OF BLOOD CELLS- HEMATOPOIESIS
3. INNATE & ADAPTIVE IMMUNITY
4. HUMORAL & CELL MEDIATED IMMUNITY
5. HUMORAL IMMUNE RESPONSE
- PRIMARY IMMUNE RESPONSE
- SECONDARY IMMUNE RESPONSE
6. ANTIBODIES
7. B LYMPHOCYTES - ACTIVATION

3. 8. ROLE OF ANTIGEN PRESENTING CELLS
9. COSTIMULATION & ROLE OF B CELLS
10. B CELL- T CELL INTERACTION
11. AUTOIMMUNITY OF B CELLS
12. ANTIBODIES IN GCF
13. VACCINES

4. INTRODUCTION…
B LYMPHOCYTES:
A WBC, agranulocyte derived from the lymphoid
series of pluripotent stem cells.
CHRONIC PERIODONTITIS:
Defined as “ An infectious disease resulting in
inflammation within the supporting tissues of the teeth,
progressive attachment loss and bone loss”

5. FORMATION OF BLOOD CELLS-
HEMATOPOIESIS
 During fetal development generation of all blood
cells occurs initially in blood & islands of yolk sac
&para aortic mesenchyme.
 Later in liver and and spleen.
 Gradually –Bone marrow (marrow of flat bones)
 Puberty- sternum, vertebra, iliac bone & ribs.

7.  All blood cells originate from a common stem cell
that becomes committed to differentiate along
particular lineages (i.e.. Erythroid, megakaryocytic,
granulocyte, monocyte & lymphocyte)
 The bone marrow is the site of all circulating blood
cells in the adult, including immature lymphocytes
& is the site of maturation of B cell maturation.

9. INNATE / NATURAL / NATIVE IMMUNITY
 Resistance to infections that an individual possesses
by virtue of his genetic & constitutional makeup.
The principal component of innate immunity:
 Physical or chemical component- epithelia, anti
microbial on epithelia surfaces
 Phagocytic cells- Neutrophils, macrophages, NK
 Blood proteins- members of complement system
inflammatory mediators
 Proteins called cytokines-regulate innate immunity

10. ADAPTIVE/SPECIFIED/ACCQUIRED IMMUNITY
 Immune response is stimulated in response to
infectious agents & increase in magnitude & defensive
capabilities with each successive exposure to
particular microbe.
 Particular characteristic- ability to remember.
- respond more vigorously.
 Components –T& B Lymphocytes & their products
2 TYPES
 Humoral immunity
 Cell mediated immunity

13. CHARACTERSTICS OF IMMUNE CELLS
CharacteristicsCharacteristics B cellB cell T cellT cell
Site of productionSite of production Bursa equivalentBursa equivalent ThymusThymus
Type of immunityType of immunity HumoralHumoral Cell mediatedCell mediated
Sub populationSub population Plasma cellsPlasma cells
Memory B cellsMemory B cells
HelperHelper
SuppressorSuppressor
Presence of IgGPresence of IgG ++ __
Presence ofPresence of
receptors for Agreceptors for Ag
++ ++
Life spanLife span ShortShort Long & shortLong & short
Secretory productsSecretory products AntibodiesAntibodies LymphokinesLymphokines

14. HUMORAL IMMUNE RESPONSE:
1. Primary immune response.
2. Secondary immune response.
PRIMARY IMMUNE RESPONSE
 The increase in Ab titre/ Ag specific T cells
resulting from exposure of a host to an Ag for the 1st
time
SECONDARY IMMUNE RESPONSE
 Subsequent the antigen is exposed 2nd
time.
 More rapid onset & longer in duration.
 Mediated by Memory B cells. They have greater
specificity Ags when compared to primary
exposure.
 IgG major role.

15. ANTIBODIES
 B cell- Plasma cells produces Antibodies/
Immunoglobulins.
 Ig- 20-25% (15mg/ml) of total serum protein(60-
70mg/ml)
 9 genetically distinct isotype of Ig: IgE
IgM, IgD, IgG1, IgG2, IgG3, IgG4, IgA1, IgA2.
 When B cell exit BM they possess receptor bearing
only IgM.
 To form secondary isotypes B cell must enter
pathway of differentiation. In this memory pathway
B cells undergo ‘isotype switching’. Eg: A.a, can be
controlled by neutrophils when opsonised by IgG
isotype.

16. STRUCTURE OF IMMUNOGLOBULIN

17.  Vl-Varaible light chains
 Vh-Variable heavy chains
 Ch- Heavy chain‘C’region
 Cl- Light chain constant
region

18. A globular protein antigen bound to antibody molecule
shows how a Ag binding site can accommodate soluble
macromolecules in their native configuration.
Red –heavy chains of Ab, Yellow- Light chains of Ag,
Blue- Antigen

20.  B LYMPHOCYTES
 DISTRIBUTION: 30% of Lymphocytes
 In peripheral blood 15-30%
 Lymph node 20%
 Bone marrow 75%
 Thymus 10%
 Tonsillar lymphocytes 50%
 Splenic lymphocytes 50%

21. ACTIVATION OF B LYMPHOCYTES
1. Synthesis of proteins
Naïve B cell large lymphocyte
Proteins are cytokines:
* stimulate growth & differentiating of
lymphocytes.
*cytokine receptors
*other protein involved in gene transcription &
cell division.

22. 2. Cellular proliferation/ Clonal expansion:
* In response to Ag & growth factor made by Ag
stimulated lymphocytes, the Ag specific lymphocytes
undergo mitotic division.
* massive clonal expansion of microbe specific
lymphocytes to keep pace with replicating microbes.
3. Differentiation into effector cells:
B lymphocytes differentiate into
* cells actively secreting & synthesizing Ab’s-
Plasma cells
* Memory B cell
4. Homeostasis- Apoptosis

24.  PLASMA CELLS
 B cells are transformed into Plasma cell-Ab secreting
cell.
 Eccentrically placed nucleus, large blocks of
chromatin located peripherally (cart wheel
appearance)
 Cytoplasm- large, abundant ER, well developed
Golgi apparatus.
 Develop at lymphoid organs- migrate to the BM.
 Survive for 2-3 days
 Expresses only surface IgM.

26.  MEMORY CELLS
 Some of the progeny of antigens stimulated B & T
lymphocytes differentiate into memory cells.
 Expresses certain isotypes of membrane Ig such as
IgG, IgE & IgA
 Occupy lymphoid tissues throughout the body .
Inactive until 2nd
exposure- Ab’s produced.

28. ROLE OF B CELL AS ANTIGEN
PRESENTING CELLS
 There 3 professional Antigen presenting cells:
1. Peripheral dentritic cells
2. Monocyte/ macrophages
3. B cells
 B cell binds to soluble antigen using BCR.
 If Ag is bound they are ingested & processed
&parts of the antigen are presented to
CD4( Helper) T cells using MHC Cl II molecule.
 Th controls the proliferation of T& B Lymphocytes.

30. CO STIMULATION & ROLE OF B CELLS
 Interaction between cells at a high level by
producing costimulatory molecule.
 Once APC’s (B cells) present Ag to T cell it gives out
a 2nd
signal.
 The most impo 2nd
signal is called CO
STIMULATION.
 Costimulation reaffirms to the Tcell that it has
recognised an undesirable Ag.
 In absence of co stimulation, T cells may become
unresponsive /apoptotic &die.

31.  Costimulation has 3 functions:
1. Prevents apoptosis.
2. Upregulates Growth factor receptor on T cells-
therby stimulating its proliferation.
3. Decreases the amount of time needed to trigger the
Tcell- Amplification

32. B CELL- T CELL INTERACTIONS
1. T CELL INDEPENDENT B CELL ANTIBODY
RESPONSE
 B cell Ag receptor (BCR) if formed partly by Ig
molecule on the B cell surface which serve as
highly specific Ag receptor.
 Therefore B cell are capable of responding to
certain Ag in the absence of T cell.
 These cells do not mature (i.e. do not enter the
memory pathway)
 These cells maintain Ig M isotype.

33. 2. T CELL DEPENDENT:
 B cells interacts with T cells – then only can enter
the memory pathway.
 B cell binds to soluble antigen using BCR.
 B cell presents Ag to CD4+T cells using Cl II MHC.
 After Ag is presented- T cell provides an Activation
signal to B cell.

34.  T cell Activators include- transmembraneous Gp39
& Gp34 which interact with B cell receptor CD40 or
OX40 respectively.
 Compensatory increase in IgM- T cell Gp39 enables
a B cell entry into memory pathway.
 Absence of Gp39- terminal differentiation of Bcell
towards Ig M ,producing plasma cells.
 B cells up regulate B7-1 &B7-2 if activated by Gp39.
 Co stimulatory factors (B 7-1, B7-2) enables Tcells to
differentiate- proliferate & production of cytokines.

35.  Some T cell cytokines are
SWITCH FACTORS:
 Th1- IL-2,IFNr
 Th2- IL-4,IL10
 Th3- TGFß
 Th1, Th2 switch on-
inflammatory Ig(IgG/Ig E)
 Th3 switch on- IgA (anti-
inflammatory isotype)

36.  Th0 – T cell matures to Th0,phenotype that is
multifaceted.
 Th1- controls altered cells,& intracellular molecule
 Th2 – important in pro inflammatory responses
against
extracellular antigens.
 Th3 – important in anti inflammatory against
extracellular
antigens.

38. B CELL PROGRESSION FROM
-GINGIVITIS TO PERIODONTITS
 Accumulating evidence, suggest that the host’s
immune response to periodonpathogens may be
different in those affected by adult periodontitis &
those resistant to the disease, in whom it would not
progress beyond gingivitis.
 In 1976 Page & Schroeder classified the progression
of gingival to periodontal inflammation as follows:

39. Clinical conditionClinical condition Histopathologic conditionHistopathologic condition
Pristine gingivaPristine gingiva Histologic perfectionHistologic perfection
Normal healthy gingivaNormal healthy gingiva Initial lesionInitial lesion
Early gingivitisEarly gingivitis Early lesion of Page & SchroederEarly lesion of Page & Schroeder
(few plasma cells)(few plasma cells)
Established gingivitisEstablished gingivitis Estb lesion with no bone loss orEstb lesion with no bone loss or
apical migration (plasma cellapical migration (plasma cell
density 10-30%)density 10-30%)
PeriodontitisPeriodontitis Estb lesion with bone loss&Estb lesion with bone loss&
apical migration from CEJapical migration from CEJ
(plasma cell density >50%)(plasma cell density >50%)

42. 1. INTIAL LESION: predominant with PMN’s.
2. EARLY LESION: T cells ↑, B cells
lymphocytes & PMN’s more than plasma cells
3. ESTABLISHED LESION: B cells↑, T cells↓
plasma cells predominant.
2 types of established lesion appear to exist:
 1 remains stable & not progress for months/yrs
(Lindhe et al 1975, Page et al 1975)
 2ND
becomes active- progressive advanced lesion

43.  Seymour et al (1979) hypothesized that a change from
T cell to B cell dominance, converted it from stability
to activity involving aggressive destruction.
 Page (1986) Gillette et al (1986) disagreed. Showed
that B cell infiltrate mainly was associated with non
progressive lesion in childhood gingivitis.
 Liljenberg et al ( 1994) compared plasma cell density
& found the density of plasma cell(51.3%) was very
much increased in active sites as compared to
inactive sites.
4. THE ADVANCED LESION:
 It is generally accepted that plasma cells are
predominant type in advanced lesions ( Garant &

44. GINGIVITIS
Strong innate immune
response
↓
Th1
↓
Cell mediated immunity
&
Protective antibody
production
↓
STABLE LESION
PERIODONTITIS
↓
Poor innate immune
response
Periodontopathic bacteria
Polyclonal B cell activation
↓
Th2
↓
Non protective antibody
production
↓
PROGRESSIVE LESION

45.  The fact is that stable lesion is mediated by Th1 cells &
progessive lesion by Th2 cells.
 The net effect of immune response to infection is regulated by a
balance between T helper (Th1 & Th2 cytoines)
 Th1 cytokines- IL2 &INF-r is to enhance cell mediated
immunity.
 Th2 cytokine IL4 is to suppress cell mediated & hence enhance
the resistance associated with humoral immunity.
 T lymphocytes predominant in the stable lesion, while
proportions f B cells & plasma cells is increased in progressive
lesion.

46.  If innate response is poor & low levels of IL 12 is
produced & a poor Th1 response occurs, it may not
contain the infection.
 Mast cell stimulation & subsequent production of IL
4 would encourage Th2 response, B cell activation&
Ab production.
 If the Ab’s are protective- clear the infection- No
progression.
 If it persists, continued B cell activation will produce
large amounts of of IL 1 & hence tissue destruction.

47.  It was also shown that decreased IL 10 allowed
continued polyclonal B cell activation.
 Also shown that CD8+T cells may participate in local
response by suppressing IFNr producing cells and
favouring humoral response.
CONCLUSION:
 A tendency for an indiviual or site to form an
extensive plasma cell infiltrate may indicate an
inability to defend against peridontopathogenic
bacteria & thus a predisposition to peridontitis.

48. B CELL & ANTIBODY REGULATION IN
PERIODONTAL DISEASE
 B cells and plasma cells produce Ig, which protect
the host by:
1. prevention of bacterial adherence.
2. inactivation of bacterial toxins
3. acting as opsonin for phagocytosis by
neutrophils.
4. antibodies can up regulate/ down regulate
immune
system.

49.  Ab’s response to P.gingivalis &
A.actinomycetemcomitans are increased in pts with
periodontal disease than without . ( Kinane et al 1993,
Mooney et al 1994)
 Naito et al (1987) demonstrated that the serum titer to
P.g was decreased in periodontitis pts following
successful therapy.
 Mooney et al (1995) conducted a study on specific Ab
avidity to P.g & A.a in periodontitis patients before
& after periodontal therapy. Found that:
-IgG levels to P.g were increased significantly

50. - In patients who had originally high levels of IgG &
IgA to P.g had demonstrated better treatment
outcomes.
- This result suggest that a pts ability to enhance his
Humoral response to suspected periodontal
pathogens&
thereby improve outcome of therapy.
 Seymour & Greenspan(1979) reported that majority of
the lymphocytes had the phenotype of B cells and
were positive for IgM & IgG.
 Lindhe et al(1980) – Periodontitis lesion:31%plasma
cells,5-10%lymphocytes, 5%fibroblast,
1.3%macrophages, 1.3%neutrophil. In the gingivitis
lesion the ratio lymphocytes-plasma cells was 1:1,in
periodontitis-1:3.

51.  Okada et al(1983) Only few PMNs were observed.
Plasma cells predominated in the central portion of
the lamina propria,with the proportion positive for
IgG,IgA & IgM accounting for 65.2%,11.2% & 1.3% of
the total infiltrating cells.
 Gillett et al(1986) : In juvenile periodontitis
biopsies,>50% of the cells were plasma cells. Lesions
in chronic adult periodontitis were dominated by
Bcells & plasma cells.
 Morinushi et al (2000 ) showed that serum anti P.
gingivalis but not anti A.a antibodies were inversely
correlated with gingival inflammation, suggesting an
inhibition of P.gingivalis antibodies.

52.  Gemmel et al (2001) found that a higher % of
CD86+cells indicated predominance if Th2 response
in both healthy/gingivitis & periodontal tissues.
 Berglundh T, Donati M (2005) found that in
periodontitis lesion, plasma cells most common-50%
of all cells. B cells-18%. Proportion of B cells larger
than T cells. The relative dominance of B cells &
plasma cells may be because of imbalance between
Th1 & Th2.
Auto immune reactions were also evident in
periodontal lesions.

53. AUTO IMMUNITY OF B CELLS
 Brandtzaeg & Kraus (1965) reported the presence of
autoAb producing plasma cells in periodontitis
lesion.
 A particular group of Bcells CD5+B (B-1a)cells are
found in large nos in peripheral blood of pts with
autoimmune disorder.
 B1 –a cells may develop into plasma cells & produce
Ig of other classes other than IgM.
 Afar et al (1992) & Berglundh et al (2002) showed B1-a
cells in periodontitis pts were 5-6 times more than
normal.

54.  Berglundh et al (1999) in a study on local & systemic
features of host response in CP before & after non
surgical periodontal therapy found that the elevated
no. of B1-a cells did not decline after therapy.
 Aramaki et al (1998) further reported that IL 10 which
is an autocrine growth factor for B1 cells was found
in higher levels in gingival tissues than peripheral
blood.
It was suggested that periodontal pathogens induce
a hyperactive IL 10 response leading to proliferation
of B1-a cells & to auto Ab production.

55. ANTIBODIES IN GCF:
 IgG is more prevalent.
 Identified about 58% B lymphocytes, 24% T
lymphocytes & 18% Mononuclear phagocytes.
 The ratio of T to B lymphocytes was 1:3 in GCF
(reversed from normal ratio of 3:1 in peripheral
blood).
In a pt with periodontal disease
1. reduction in Ab response is detrimental
2. Ab response plays a protective role
( Lamster IB, Celenti R, 1990)

56. VACCINES
 Passive immunization of humans using monoclonal
Ab’s temporarily prevents colonization of
P.gingivalis.
 Gemmell et al (2004) used F. nucleatum & P.
gingivalis bacteria in immunisation schedule. Results
showed that a vaccine candidate maybe enhanced by
combination of both. Raised IgG1 and IgG2 were
seen.