This document discusses multiple immune responses against parasites. It describes avoidance behaviors, grooming, antibody production, eosinophils, granuloma formation, and pustule development as initial responses against ticks. It also discusses refractory and susceptible responses to different parasites depending on the host, as well as antibody-mediated immunity against extracellular protozoa. Further immune responses discussed include immune expulsion of gut nematodes mediated by secretory antigens, antibodies, and mast cell degranulation. The document also examines cutaneous hypersensitivity responses types 1 and 4 against mites, ticks and fleas, eosinophil responses against tissue-based helminths, macrophage activation against intracellular protozoa, cytotoxic T lymphocyte responses against The

1. IMMUNITY PARASITES MULTIPLE RESPONSES AGAINST PARASITE
eg. cattle responses to Boophilus tick
!
AVOIDANCE
GROOMING
ANTIBODY
EOSINOPHILS
GRANULOMA
PUSTULE

2. IMMUNITY PARASITES REFRACTORINESS / SUSCEPTIBILITY
• Rhipicephalus sanguineus infected with Babesia canis
grooming evasion of antibody evasion of phagocytosis
• Ixodes ricinus infected with Borrelia burgdorferi
Ab
grooming wrong receptors phagocytosis
(human is refractory)
(human is partial refractory / susceptible)
spirochaetes in
joint

3. IMMUNITY PARSITES ANTIBODY ON EXTRACELLULAR PROTOZOA
eg. Trypanosoma in blood plasma
surface antigen membrane lysis
+
+
+
+
+
+
+
+
+
+
+
+
C3b complement
complement mediated
lysis and opsonisation +
phagocytosis
Th
B

4. IMMUNITY PARASITES IMMUNE EXPULSION OF GUT NEMATODES
U
U
B
Th
U U
secretory
antigen antibody
nematode inactivation nematode expulsion
stimulation of goblet cells
+ type 1 hypersensitivity
releasing mast cell amines
aid expulsion of inactive
worms
stimulatory factors
gut with goblet cells

5. IMMUNITY PARASITES CUTANEOUS HYPERSENSITIVITY - TYPE 1
Types 1 and 4 are both active against mites, ticks, fleas
• TYPE 1 produces amines leading to eosinophil
degranulation protein which is toxic to macro-parasites.
IgE antibody
antigen
histamine
serotonin
eosinophils basophils neutrophils
sensitised mast cell
degranulates when
exposed to antigen
attraction of granulocytes

6. IMMUNITY PARASITES CUTANEOUS HYPERSENSITIVITY - TYPE 4
Types 4 and 1 are both active against mites, ticks, fleas
• TYPE 4 activates macrophages which stimulate
fibroblasts to produce granuloma and neutrophils
to form intra-epidermal pustules
T cell
sensitised T lymphocyte
releases lymphokines
macrophage
activation
neutrophils
lymphocytes
antigen
fibroblasts

7. IMMUNITY PARASITES EOSINOPHILS AGAINST HELMINTHS IN TISSUE
Antibody mediated cytotoxicity against Schistosoma,
Fasciola etc
• Secretory / excretory antigens stimulate production of
antibody from B lymphocytes and eosinophil
stimulation promoter from T lymphocytes.
• Antibody opsonises helminth larva, eosinophils
degranulate around it and kill it.
B
Th
antigen
Y
Y
Y Y
Y Fc
Fc Fc
antibody
eosinophil stimulation
degranulation
opsonisation

8. IMMUNITY PARASITES MACROPHAGE ACTIVATION AGAINST
INTRACELLULAR PROTOZOA (eg Leishmania)
• Type 4 hypersensitivity: antigen stimulates T
lymphocytes to produce interferon gamma. This activates
infected macrophages to produce NO and H2O2 and
extra lysosomal enzymes, all toxic to Leishmania
APC T cell
activated macrophage kills Leishmania
antigen
Leishmania in
parasitophorous
vesicle within
macrophage

9. IMMUNITY PARASITES CYTOTOXIC T LYMPHOCYTES AGAINST
INTRACELLULAR PROTOZOA eg Theileria parva
• Antigen is presented to CTL and they proliferate.
• Antigen + MHC receptors on CTL permit specific
binding to infected lymphocytes.
• Bound CTL release toxic granules to kill infected cell.
T lymphocyte with Theileria schizont T lymphocyte killed
APC
CTL
CTL
antigen released
specific
granule release

10. IMMUNITY PARASITES EVASION OF ANTIBODY BY ANTIGENIC
VARIATION in Trypanosoma
• Trypanosoma antigens stimulate antibody production.
• These antigens can vary in successive generations of
Trypanosoma.
• Each new variant can evade the preceding antibody
response until new antibody is produced.
a
b
c
d
a b c d
Trypanosoma per
mm3 of blood,
variants a - d
Titre of antibody to
variants a - d
Time (each peak takes several weeks)